Am I developing feelings for my guy friend but he has a girlfriend?

He was the one who initiated our friendship and he keeps flirting with me all the time. At first I used to take it as a joke but then since he kept coming on to me so much (I do find him attractive and we have a lot of sexual tension) I think I'm starting to develop feelings for him now I'm not sure though. Like the thought of him being with another girl makes me jealous. And he too gets jealous when other guys flirt with me.

He has tried being intimate with me as well but I didn't encourage him so nothing physically happened between but we were pretty close to it. Apart from this flirting and sexual tension, he keeps complimenting me on my personality too like how he thinks I'm cute, how he loves my laughter, my presence, how I look pretty when I wear dresses, etc.

I had stopped talking to him like 2 months back (because I didn't want to get involved with a guy who has a girlfriend) and he was very upset by that. Now I haven't seen him for 2 weeks and I can't help but miss him. I don't understand what's going on.
Am I developing feelings for my guy friend but he has a girlfriend?
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