Hopefully I can give you some insight from the eyes of a male that does the exact same.. I've been doing this for 6 years with a girl that I absolutely love and want to start a life with.
We're all different and it's hard to really say without knowing how his whole life story of his struggles and coping mechanisms. So here's my story hopefully it gives some understanding..
he broke up with me out of the blue. He's bipolar subtype. Everything was going extremely well, we were super connected and the best friends in the world.
I usually would last a few months of intense love and being able to show and give it to her, Then comes the inner turmoil and chatter leading me to my coping mechanism, dropping her and everything out of my life so I can feel safe and comfortable in my own silence from the world.
He just said that the spark is gone, even though is still loves me. It's like one day he woke up and just forget the feelings he had]
In my shoes, and as others have pointed out. For me that was a good indicator that i'm entering a depressive place disconnected from others and feelings. There's nothing you can do for him except support him and be very gentle letting him know it's ok. (If you choose this route)
For me sex can trigger that as well.. the over flooding of intimate emotions would eat me up and couldn't handle the emotions, so I shut off.
I don't want to cling to the relationship either if it's not the case an that's really how he fells now and will feel in a few months down the road. I know this type of breakup is common for bipolar, but I don't want to hurt myself in the process by getting false hope. Any of your input would be greatly appreciated, many thanks.
Unless you absolutely love this man, and are willing to make life sacrifices around his limits, be careful. I've caused so much heart ache, not out of choice, but my coping mechanisms.
AND most importantly.. if he's not on medicine and or getting therapy, I'd recommend backing up from the intimate level, it will more than likely happen again. I did it 6 times before the right dose and cocktail of medication. But love is love, Decide if you're really willing to be on his rollercoaster. Make sure it's 50/50.. You need to do what's best for you.