Everyone having sex but me 😒

My bf has been acting a little different lately and idk what to do. He's always on his phone, if I don't text him he won't text me at all, sometimes he ignores my texts, and he doesn't really wanna have sex anymore. It's always me the one who has to initiate it and even like that he rejects me sometimes. I'm starting to think it's because I'm pregnant and I'm starting to get stretch marks all over. Or simply because he's getting tired of me. He used to be so loving and he's sex drive was always high, our sex life was great. 🙁 Not to sure what to do since I already tried talking to him.