I know personally both me and my boyfriend are struggling with some kind of depression and anxiety. He's been diagnosed and while I haven't been, I've had anxiety all my life (so I feel for you! <3) and on-and-off will experience symptoms of depression: general sadness, crying, lack of energy, and here's the kicker: lack of interest in doing the things I used to love. I have found my feelings of attractiveness and libido have gone down so much that I am rarely "in the mood."

If he's experiencing depression or any other mental health issue, that could be the reason (as he said, it has nothing to do with you). It can be hard for anyone to talk about their mental health. Maybe try sitting down with him and talk about how he's really doing, and try not to bring up your own anxieties (because if he IS feeling depressed, you don't want to take that away from him in this conversation. Not that your feelings aren't important, too, but just when you make that initial inquiry). Make the talk about him and show that you're concerned about him and that you love him.

Sorry you're going through this, but you are not alone! Let us know how we can help.