<human>: Can you summarize the given text in a few sentences?

I(22 f) have been with my boyfriend (23 m) for 1.5 years. I don't have any complaints, except the tiny things that irk me. More than anything, I'm not complaining but just wondering why he does this.

1. Today he felt the need to reference "the cute cashier that seemed like she was flirting with me at the pet store." He was telling a story and this came up. And when we go to parties (which isn't all that often), he will comment about how cute that girl's butt was, or whatever, after we are back at his house for the night. He doesn't even talk to these girls but he feels the need to mention their ass to me.

2. I thanked him for buying me food and he utterly would not accept my thanks and just came up with snarky sarcastic remarks. Told me I should not be thanking him for everything he does. What? I thought guys LOVE to hear that their girlfriends appreciate them. Then his friend thanked him and he said "no problem man."

3. His exes come up a lot in stories. Actually, he brings up his past quite often (not just exes, but friends from high school and elementary school). He doesn't talk to any of his exes but tells long stories about them and expects me to find the stories interesting. I've told him I don't like hearing about his exes but he still talks about them.

I brush these things off when they happen but now I'm home alone and wondering, why does he do these things?
<bot>: My boyfriend brings up exes, makes references to other girls, and won't except my thanks. Why does he do these things?