This sounds like I could have written it myself about my previous situation.
It started as a drunk hook up with my friend, we decided to carry on as fwb as he said he didn’t want a relationship. I decided that was fine as the sex was great and we got on so well and both were on the same page. It essentially turned in to more like dating (talking daily, seeing each other at least once a week, sleepovers) but still pretending it was just fwb.
all I asked of him was to be honest and upfront if he had met someone or wanted to call quits. He said he would. He didn’t. He just tried to drift and the mood changed, I questioned if, he said he just wasn’t in a good mood, I let it go. It carried on like this for another month until I called him out and he ended it “as he didn’t want to hurt me”. I then found out 4 weeks later that he was seeing someone else.
fwb doesn’t work as soon as you catch feelings. You can pretend you don’t but in the long run, if you’ve already started to question why he has withdrawn or if you could want more, then it’s just going to develop. It only works if there are clear boundaries.
Its tough to break away from that situation but the last guy I went on a few dates with in Feb was perfect for me but he only wanted casual and despite me wanting him, I knew I’d end up getting hurt so had to think of myself and say no.
long story short, you’re not alone in feeling like this but I’d have a really good think about if you do like him more then just a shag and if so, tell him and see if he reciprocates and if not, get out and protect your feelings.