Why did this happen

So, my and my boyfriend broke up 2 weeks ago, almost 3 weeks. We had sex last Friday night, and he was talking to me like we where just back together.....

But then he made no further plans that week to see me and we argued a lot over the phone where he told me he still didn't want to work things out because we've tried everything! And it didn't work.

He then called in a few times to see me and our daughters, but I kept strong, kept happy, and avoided any kind of contact (kissing, hugs, sex etc) I kept it casual.

He called in on Saturday to collect our daughter to bring her up to stay with him. And while he was here he was all over me.... grabbing me, kissing me. It made me slightly uncomfortable bevause as much as I still want him. I had to hold my grounds. So that I'm not head fucked. I asked him nicely to leave and not to mess with my head so he did.

He then text me to apologise for it.

Sunday evening, he called back to drop out daughter off. And he hung around all night. Staring at me, being flirty as hell with me. But he looked so uncomfortable (because of how happy and confident and strong I kept)

So he kept his distance while making eye contact with me all night. We both fell asleep on the sofa. And nothing happened.

This morning as he was leaving he kept staring at me again, making eye contact. Then before he left he slowly made his way in for a kiss. Because of how passionate the whole moment felt and because of my seriously strong feelings for this man. I caved. I kissed him back.

One thing started to very slowly lead to another. But just as we went to do it, he went soft.

It made me feel like, so uncomfortable and awkward and paranoid. I thought that given our feelings toward each other and our history and it being a while, he would be well excited for it. So why did I get this reaction.

It did look a little to be out of nerves. He seemed very nervous.

Once I got paranoid he took a moment. Then came back hard and ready. And he didn't last very long.

Could it have been a nervous thing? Or did I cave too easily and quickly and he's just not into me the same?

It's going to melt my head all day.