Worried about my boyfriend

My bf has been acting a bit different lately. We live together. I don’t know if he’s sad / depressed ?

I’ve asked him a few times if he’s ok. He says yes. I told him that he can talk about it with me but he hasn’t. He says it’s just his job. But he acts like this even on the weekends when he doesn’t work.

I’m worried about him. He has been different with me too so I wonder if it has something to do with me. But I don’t know what I did

He’s not talking to me as much. He just lays around on his phone. And plays video games. He doesn’t joke with me as much. He doesn’t try to have sex with me everyday like he normally does. I’m just worried.

His birthday is coming up in a few days. I don’t know if it has something to do with that.