That's a hard one! Sometimes we watch a frienship slowly die and wish there had been a confrontation instead. If this friend means a lot to you, I'd have a serious conversation with them. It takes two to keep a friendship alive. I believe there are things you must do if you want to keep a friend. It's almost like tending a garden. It really hurts to think the other person has other priorities and has no time for the friendship anymore. I've been there and hate that you're facing it now. Honesty is the best policy I think. Voice your concerns and see what response you get.

bumping this one back up

Talk to them.let them no.how you feel.hope evertyhing works out. Hugs to you. and your friend.

I agree with both above
Voice your concerns-tell them how you feel
see how that goes

Talk to your friend and explain why you don't think things are the same.
Hopefully you will work it out and stay friends.

I have a similar issue with a friend that I have known since college (over ten years now for me) and we used to be really close...but our relationship has gotten more and more strained over recent years. We have gone months without speaking at times and knowing that he has had other friends fall out with him that he has made the effort to reach out to so as not to lose them, it bothers me that much more that he does not do the same for me. Our most recent spat I'm not even sure is one - I told him about my dog passing and his reply was like sorry to hear it now here's what's going on with me. He knew how much my dog meant to me so his blatant disregard for how I was feeling about losing her pissed me off and I called him out for making like it was no big deal and like his news was just as relevant at the time that he needed to share it with me at that moment rather than be a friend and show support to me. I haven't spoken to him since and he hasn't reached out to me. I don't intend to reach out to him either because his actions finally made me realize that I wasn't getting anything out of being his friend anymore.
I have had many friends disappear on me over the years...more so than any arguement or other issue. Usually, as time goes on and you drift apart because your lives are going in different directions, you kinda just sense that things aren't what they used to be. If you are lucky you do get the chance to make a proper goodbye or at least hash out whatever has caused a rift between you. But I think the quiet disconnect is the worst, because all you can do is wonder why things fell apart, especially if you were once really close. I suppose if you do not want to see the friendship die or you at least want to give it a proper end, then you should try to get in touch with your friend and work out why things have gotten to the point they have between you and determine whether you want to allow things to end or whether you both want to work on repairing your bond.Much like with a marriage only there's no need for a divorce lawyer if you choose to walk away from each other.
I may contact my friend, eventually, but at this point I'm still annoyed with him and so I'm not going to be doing that right now because his attitude hurt me and his not realizing it hurts that much more. Knowing him and how egocentric he has gotten, he's annoyed that I wasn't more celabratory about his news. But that's the difference between us I guess...I can forsee how he saw that exchange and he can't see how I saw it.
Good luck with your friend. I hope it all works out for you, one way or the other.

If the gulf between you has widened it may be a good idea to collect your thoughts as to the wisdom of just letting nature take its course. Sometimes it is better to just accept things as they are rather than "to work to save a failing friendship."

Has life taken you down different paths away from each other. Memories may not be enough glue to repair what is not there any more.Friendships should be a pleasure. It is ok to grow away & to go away. That is the stuff of life.

Are your feelings for this friendship based on the future & what is to be or just on what has been? If you find that you are just longing for the past perhaps it is best to just let go. But if there is more than that to it then by all means approach your friend as soon as possible to see what can be done to begin a bail out of your sinking ship.

NDY