As your YF enjoys your friendship and you like him I do not think that you should push him away.
In two or three years time he will move on and you will have gained the experience of self control that will make life much easier for you in the future.
Everybody is faced with temptations but we have the advantage of the bible and the law to help us remain celibate.

This Scripture is remarkably true: Corinthians 10:13 that "No temptation has seized you except what is common to man. And God is faithful; He will not let you be tempted beyond what you can bear. But when you are tempted, He will also provide a way out so that you can stand up under it."