Tmi in some parts... need advice

So i was seeing a guy for a few months. Nothing serious. Just fun. It started off amazing. Lots of lovely chatty wee texts everyday. Wanting to see me alot. Sex was amazing. We where both like... WOW after it. Outgoing and having fun with eachother. I was so happy. BUT.... then he started to talk some future talk about us during convo things like about kids and him not wanting more and asking me do i etc. Saying things like "when we live together" telling me he had feelings for me it was more than sex to him etc. Yet. On a stupid night of getting totally drunk and trying my first ecstasy tab i opened up my heart alot. About past hurt in relationships. How down i still am. How little confidence i acc have and lack of self esteem etc. At the time it did seen like he was listening but in all fairness i think i just melted his head and ruined his fun night for sex. And after that night things between us changed. He stopped textinf alot. Wasnt as 'attached' or emotionally there. Stopped being caring and intimate. Just went cold fish like he was trying to back off and make me back off. So due to this it did all get awkward i did lack then alot more confidence on the outside being so paranoid he didnt like me anymore. I started to ask questions on what was up and what he wanted out of the relationship and things got more distant. So when i tried to walk away ans leave it. He 'acted' devistated and pulled me back in. After a long talk one night in the car he seemed so mature and decent about it all telling me he still felt the same way about me im a great girl and i deserve it all. But he cant give me that righr now with his kids still beibg so young there happiness means more and he stopped texting for my benefit so he wasnt leading me on anymore etc etc. Then he asked me to spend a night wity him in 2 weeks time. So i agreed and the whole two weeks leading up to it NOTHING no texts. No communication. Then that night came up and i heard from him. So i went to stay with hin. This time holding myself back. Wasnt chatting much didnt try to hug or kiss or be intimate with him. We watched a movie that was all ok. Then the sex came and boy was it different than before. awkward.... i just couldnt get arroused at all ans was really not feeling it. My vagine kept drying up quick causing friction etc. My mind just knew too much that he wasnt in to ne anymore and that he was using me now. So i spent more time doing oral on him than anything and during sex it just slipped out if my mouth i said "this just isnt working at all" and i got off him and lay down. I did then try to lay on him after and he wasnt having it. He just wanted to then sleep. Get up next day. Acted weird and off. Dropped me home. And thar was that. Never heard from him again. I have been missing him so mych as i did feel we originally did have alot of connection and i dont get how he coykr feel 'nothing' at all threw all that time with me ans walk away. What went wrong? What did i do? Would he have sensed and new i wasnt sexually aroused? Would that have made him loose confidence? Or make him paranoid? Woukd it have been enough to make him run?