Say something or enjoy the ride?

The first 6 months I was my mans only gf. Our sex was awesome. He came in me all the time. It’s the first time I let and wanted a man to do that. We talk about pregnancy and having a family might be on our agenda. Now he’s started talking to his ex of 12 years. I know they bang. I know (kinda- I can guess) when they do it. Anyway. Ever since (for the last month) our sex has decreased. And when we do have sex only I cum. He doesn’t cum or get on top of me. Am I doing something wrong? Am I not as good in bed? Do I ask him about it? Wtf. I tried looking up tips and tricks- u know- to be competitive- but doesn’t seem to work?? It’s like there’s no cum left for me? Does it matter if we aren’t planning a baby now anyway? Who knows- maybe we won’t ever. Maybe I should just pay it no attention and enjoy the sex....