No jiggy time

My boyfriend and I are 21 and 23. We have a great time together, and we’ve been dating for 3 months now. Recently, we’ve been having sex less and less and everytime I bring it up I start crying and he says it has nothing to do with me and he’s just going through a funk or is tired. After we had sex the other day, he said he got a scab from chafing and said we should take it easy on the sex. We still sometimes do go replay but not as much as we used to. I can’t help but take it personally and feel ugly, unwanted, and worthless, even though I’ve been reassured that it’s him and not me. Should I be concerned that it’s something else?? Or....someone else???