Anxiety Support Group
Anxiety is a physical condition marked by intense and persistent feelings of distress, fear, angst or dread. General anxiety caused by routine day-to-day stresses usually passes quickly and is experienced by almost everyone at one time or another. However, such feelings that linger over time and are very difficult to cope with, and which lack a clear cause, may indicate...

Writing it out in a safe way (private journal) usually provides some clues to help you move through the pattern,
Practice even breathing and stop, pause, breathe, option, repeat until calm before saying or doing anything while in active anxiety.
These are just suggestions.
Welcome to anxiety board.
granting that i didn't date when i was eligible and have been married over 40 years, i treat relationship anxiety like social anxiety. of course i use the term, "relationship" as a generic term. if you are using the purely sexual context, you might do better to listen to the chick flicks than me. i often wonder if they are the chief inventors and manufacturers of the specialized "relationship anxiety."
i have an entire tool box of social anxiety tools, but? ? ? i'm not sure they fit here. i mostly wanted to welcome you to the forum.
Long distance dating can cause anxiety, even in the best of circumstances. I was in a long distance relationship in my teens, but we had dated in person for 6 months before he had to move away. We still saw each other almost every weekend. It took effort and commitment to keep things going with us, once it went long distance. It is definitely more work, so be gentle with yourself.
How far away does he live? Is there talk of getting together in person any time soon?
It's hard, I know. Keep yourself busy with local friends, your family, your school, your job if you work, your hobbies. It's kind of too soon to sink all of your hopes and dreams into this guy just yet. Especially if he's already acting strange. Take your time, go slow. Keep busy with your friends. It will help you to feel better.
Let us know how it goes.
Seems to me you’ve already labeled him as perfect when no human being is perfect. No wonder you are anxious! I’d be, too, if I was thinking he’s perfect but I’m not. Slow down. Do the self introspection others on here have mentioned as what is the source of the anxiety. Could be your internal wisdom saying slow down, no one is perfect, listen and observe.
Long distance relationships take longer to really prove out. You don’t really know someone till you are local and are around their home, car, work, friends, family. It’s easy to hide the bad in an LTR so just don’t be desperate.