<human>: Can you summarize the given text in a few sentences?

I started seeing a guy last year and things were great between us. It was a fun casual relationship and we had fun together. We saw each other regularly and had wild fun sex but we weren't exclusive. This was clear to both of us. 

I honestly don't know why out of nowhere, we started to see each other less. I made efforts to make plans, but he was often busy. I'm not stupid, I got the hint. But we remained friends... I was going to leave it alone but the conversation was often initiated by him, I didn't mind so I responded. 

There was more 'spending time together' but sex was no longer part of it because he was clearly not making a move. ( I made a few and they were *politely* ignored, so I stopped. We stayed friends.

Now we rarely hang out, and I get it, he's not interested. I've moved on but I'm disappointed because I liked the time spent together and wanted it to continue, I am fine with being friends even though, that's obviously out of the question now. My question is, is it weird to ask him why he lost interest? I am genuinely curious to know because things seems so great before. It is unrealistic to expect a casual 'boyfriend' to *break up* officially instead of fading out slowly?

I asked him over chat why, and got no response.
<bot>: Dated a guy for a while, things fizzled out, asked him why but didn't get an answer. Is it stupid of me to want to know the reason? Is it asking to much to expect one?