Once you are on to the scent it is pretty easy to confirm.

Look at credit card and phone bills.

If you have the password to his social media and phone just take a look at his messaging and browser history.

If you don't have them then it is already a red flag that he may be hiding something.

If this is the case then just randomly ask him for his phone and password one day.

If he refuses or tells you he will let you see the phone in an hour (after deleting everything)...then he is cheating because there would be no other reason to refuse.

That's pretty much how it always happens. Very few cheaters come clean the first time you ask. Mostly, they make you prove it to them.

It doesn't matter if they are sleeping together, he's probably knee deep in an emotional affair. Women have a good nose for when their husband is really switched on while talking to or about another woman. That's usually the first big red flag.

Check the easy stuff first. Look in his wallet for receipts that look like dinner or lunch for two, condoms, Phone numbers written on scratch paper or business cards with someone's handwritten number on the back. Usually numbers go directly into the cell phone these days, but cheating spouses like little mementos of the OW, tangible things they can hold. Look for things that seem out of place, different or odd. Is he working more hours? Is he not returning your calls or texts mostly during lunch and right after work? You know him better than anyone else.

Check his social media, phone and stuff like that. Instead of asking him to check his phone, I'd get on line and pull the phone logs. Then you'll have something to zero in on. Good luck!

Would his co-worker know if he's married? Is she single? If so, and you're both on Facebook, use the 'View As...' feature to check his profile to see if he's hiding his marital status or hiding posts where you are tagged. Does he dislike you tagging him? Does he tag you?

If he's using Android and you can guess his Google password you can check his browser history remotely without needing physical access to his PC. And if he's using Google photos, calendar and Gmail you'll get all of that with a single logon.

The phone bill is the first place to start. Bring up the bill and look at the usage. Calls, texts to a strange number or repeated at certain times of the day or night. If you can narrow down a time when he is texting her and it's pretty regular, wait till some night when you see him texting and ask him who he's texting? If he gives you the name of someone you know and have a phone number for, check the bill again and see if he was lying. If he was, you got your proof. That's when the back peddling will start. Print the bill out and hi-lite the number as many times as you see it. Cheaters think they are very smart and know how to cover their tracks but they always miss something. They get sloppy too.
Right now, I have two people asking themselves 'How the hell did he know all of this? We were so careful and slick' The words right out of my wife's mouth last weekend, And apparently he hasn't figured it out yet either. Get proof, have it available and SAVE it.

In the age of technology there is always a trail and fortunately or unfortunately all you need is an unlocked phone and you pretty much have access to everything.

Does he have his phone on him and never puts it down? Even in the bathroom or shower? Does he have a work phone? If he has a iPhone and you know his iCloud password you can use find my iPhone and track him (unless he leaves his phone at home)
Go through his car, phone bill, cc statement, checking account, all apps! They support private chats. Of course they think we don’t know that (of course the are playing candy crush at 2 am) hell this site you can message privately... car sites, gun sites, ect

Trust your gut feeling it's usually right. There's some good tips above on how to het your proof. He surely won't admit unless you find proof. If text messages ate deleted you can still see if texts were sent through the phone log. If you see 1 number with lots of deleted messages that's suspicious. Also go on his computer and phone and go in internet search history. That's usually pretty eye opening sadly.
Please get STD tested once you find proof. Cheaters never use protection. So sorry for wgat he's putting you through

As I said, they think their smart. When my wife started to realize that I was on to her, she and the D-Bag started to wonder how I knew. Their first thought was a tracker on her phone so my wife would leave (forget, she would say) her phone here at the house. She has since admitted that she would leave it at work if she had it with her. Then she thought I had a GPS tracker in her car and the D-Bag would come and pick her up at work to head to the hotel. I always knew there was one thing my wife never went anywhere without, her pocketbook. That was where the GPS tracker was. When I had cameras in her cars, I would move them to different spots whenever they were in there. I had different views to see, front and back areas of her SUV's. Once they started leaving her car at work, the cameras were no good anymore of course. Not sure what a man would always have with him to put a GPS in??? But, if they take their phone with them everywhere then the tracker on the phone would work well unless they get an idea about it. Maybe we could develop a "Cheater's Chip" to implant? You know, like what they put in dogs. Well, we would still be putting the chip in a dog wouldn't we?

Something that always worked for me and was the first sign is habits. My wife was a creature of habits and when she started to deviate from them, I knew something was up. We had that computer on the desk for 5 years and my wife never touched it till that night she went in and did a Google search for an old friend. I asked her what she was doing and she told me she was sending an email to her sister. First lie of many. I looked at the search history and saw his name. That was when I started writing things down. Now she was going on that computer on a regular basis. Problem was, I had set that computer up and put in all the screennames and passwords and even though she thought she was safe when she deleted his emails, you had to go into TRASH to get rid of them for good. She never knew that. Once she realized I had access to things, she told him to use her work email. Trail went cold until she started to send text a few months (years) later.

Reading these posts makes me realize that I am not alone. But what to do? What to do? My husband started texting another gal last year. I always thought that texting another of the opposite outside of work related issues was wrong. Like we used to think of telephoning another of the opposite sex outside of work was wrong. Does anyone out there think it is acceptable? To my knowledge it has not developed into an affair, but this is how affairs can easily start.

I don't feel crazy for doing ok of those things to catch my bf/husband over the years. He says I'm a stalker, I say it as the only way to find out a little about the person I am living with. I don't want to live that way forever...

Several wise people told me: a man doesn't invest in spending time with a women unless he has some hope for more to happen. I dont mean this to offend any men on here at all, but I sure think its true. A true friendship between man and women is of course possible, but than its more a friend from the past, a family friend or a friend of both of you as in that he would have introduced you to her and her husband for a couples meet up. A female colleague at work that he suddenly want to be friends with, ya very suspicious for cheating or going to cheat if it hasn't happened yet.

Base on your replies, I know he is cheating. I absolutely knew. Maybe Im in my denial stage momentarily. But now I realized I have to focus on my pregnancy instead of thinking him, I should think first my baby. Im 6 months pregnant right now. I have to open this up to you to lighten up my load. Thank you for all your responses and concerns. I have to stand up for my child. After being a crybaby on my husband, I will now move on. WILL DEFINITELY TRY HARD TO MOVE ON! This is my first step. Thank you Guys! <3

I hope this kind of situation will never happen to any wives around the globe because its very painful to the point you cannot explain how much it hurts.

I'm sorry you're having to go through this. Take care of yourself and your baby first and foremost. Please tell your OB your suspicions and get thoroughly tested for STDs. Some diseases have dire consequences for the unborn but can be at least treated if the Docs know what they are dealing with. So many people cheat on their pregnant partners. It is so common its staggering but I realize this gives you no solace. You are not alone. ALWAYS trust your gut. Please read my post "Welcome to the newly betrayed" for some practical first steps. I wish you and your baby well.

I'm so sorry he's putting you through this my hart sinks hearing your pregnant. Please get tested asap for STD. There have been some sad posts on here from B.S. getting STDs and now there's an unborn baby at risk too. It sadly happens way to often.
Stay strong you can do this

Be suspect whenever a spouse has friends of the opposite sex. As someone mentioned, this is how affairs start, as friends.

When a CS is caught and has to answer how this all started....it is usually along the lines of how it was just a friendship and that they didn't expect this to happen.

My wife no longer has any one on one male friendships or private communication with men.

In our case it is obviously that my wife isn't trustworthy to maintain any male friends but for relationships that haven't been affected by affairs still need to draw clear boundaries at some degree as sadly this is how most affairs start.