OP I dont know if you can.
But I felt the same about my best friend. We were both recently single when we met but not interested in anymore with anyone. Looking back, we acted like a couple. We went for days out together, cinema, dinner, did food shopping together, slept at eachothers houses all the time. We were rarely apart and always in contact.
Then it ramped up and we slept together. I still didn't want an official relationship. Neither did he and we ended up in limbo for months which was great and awful. I mean we still did everything together and had sex but weren't a couple.
We then had a fall out. Quite a spectacular one where I told he him we were done. He told me he was relieved 
. We were both as bad as eachother. But I remember thinking that if he could be happier without me, that's what I wanted for him.
That's when I knew I loved him. I would rather not have him in my life, if that's what would make him happiest. I would take the hurt and eventually move on as long as he was Ok.
Anyway, he called me the next day and we made up.
Then I realised I couldnt do this anymore with him. He came round for breakfast the next morning we talked. From his point of view the fallout happened because he was edge that I was just sleeping with him until I found someone I did want to get in a relationship with. He thought lt I would just walk away one day. I was stressed because I knew the path we were in would lead to disaster and the thought of losing him made me ill.
Anyway long story short, we no live together with my son. My son has always thought the world of him. My son also asked me why it took us so long to get together. 
I know it's a long post. But if you genuinely feel so strongly about him, something will have to give at some point. There will be a breaking point. It's better to speak up and tell him, than get to the point you cant be around him. The feeling probably wont go away on it's own.
Me and dp nearly lost eachother. Dont let that happen.