Darling, You're 23, and I'm guessing you have a hot bod? Sexual tension is going to be everywhere you look for at least the next 20 years. Enjoy it, use it and just see it for what it is. Without sexual desire how could we possibly meet any of our partners?
It's a shame that the two of you never had the chance to give this tension a little test. I guess you could
call it bad timing. Leave it at that. Movies aren't real, there's no unforeseen reason or force that has stopped you from meeting the love of your life.
But don't sweat it, hot chica. It'll happen again with another guy... or maybe even another girl. I promise. I've never believed in the whole "one soul mate" thing. We come across many in one lifetime, and we're always given a chance to go for it. Of course, if we don't take that chance there is always that nagging "What if?" feeling. Life is about taking that chance and going for it.
So look at this guy as one of those "What ifs?", and leave it at that. You can use him for, you know, "creative visualization" on dark and lonely nights. I mean, men have their spank banks, why can't we? Besides, sometimes fantasies are better left fantasies. I can't tell you how of my "fantasies" ended up being terrible lays and disappointing relationships.
But hey, a long distance flirt is always nice, just so long as you both understand that it's nothing more. Sure, send him a message. It'll probably turn out to be exactly the way you fantasize it to be: fun with a bit of sexual banter. Just keep it all in check. You live in Shanghai. He lives wherever he lives. There's no point in expecting any kind of commitment.
Ultimately, you're a 23-old with a hot body in Shanghai. You shouldn't anchor yourself to some guy on the other side of the world. Get out, and have fun! You never know. You may just find someone here who sweeps you off your feet.