As the others have said, this is not a good idea on so many levels. Who knows, maybe you and he have a really special bond and will know each other for the rest of your lives. But you may not. I don't think at this stage you can tell and the safest thing to do at the moment would be to at the very least delay this for a few years.

FWIW, I fell in love with a gay man when I was 18. He said he loved me too. We were both happy with the fact that we would never have sex and discussed getting married because at the time we wanted to spend the rest of our lives together. Our friendship/relationship lasted for 18 months and we barely had contact after that.

It's much too soon to be contemplating this.