Sex Trouble

So my boyfriend and I have a great sex life. But lately things have been off. Now I don't have an orgasm easily or every time but it's been 3 weeks and I just can't seem to get there. My boyfriend has been having difficulty it in lately as well. It's like I'm a virgin again (no pain or blood though)- I'm just so tight. And I've also started crying during sex a few times. I just don't know what this could be. I'm still attracted to him and I love him. We're not fighting. I have been more stressed and emotional lately but that's it. There's no other changes. I just don't know what's wrong with me.