Questioning my relationship

So I don't know if I'm just pmsing or if I'm just all of the sudden losing interest, but I'm all nervous about my relationship. We've been together for a year, we fight probably an average amount and I love him, he's my boy. But at the same time, it seems like I've suddenly, as in the past week or so, just become endlessly frustrated with him. Most of the things he says bores me and when I want to say something, he changes the subject. I told him I didn't want to have sex tonight, and I end up bent over for 45 minutes. Like, I love him, I know I do, but what is this? Am I not in love? Am I having these emotions because of PMS? Someone help, I could really use some advice