Should I be concerned?

My bf and I have been together for four years. We both live with our own families still, just saving as much as we can. We both work full time, so we only see each other once a week (usually Saturdays) and have a sleepover. Our sex life has always been really good, we’ve always been super compatible in that sense. But lately, he’s not been initiating it at all with me. Sometimes I’ll have to initiate it. It’s kind of scaring me a little. Last weekend was our four year anniversary, and we didn’t have sex at all. We were tired after a long day, but not even the morning after. He just doesn’t get turned on at all. I know he watches porn and I’m just wondering if he’s watching even more now? He’s not flirty with me or sexual with me AT ALL. Should I be scared? lol….