Online relationship that means a lot to me

I've been online dating for 5 months now and I love him a LOT but he loves me more, in fact he wants to marry me a few years later but I don't think we are meant for eachother, I don't see that spark even though I love him so much. Yesterday I told him I didn't wanna get married cause we're different people living in different cities, and I don't see us as the forever kind, and he ended it saying we'd just be friends as he can't do a casual relationship, cause relationships have to have a goal for him, and I'm super hurt and way too attached to him so I don't wanna let go, but at the same time I know I'm causing him pain, I don't know what to do