If a guy truly loves a girl do u think he'll wait until she's ready to have sex with him even if he'll have to wait, say for about 3 years?

Yes but I am guessing you are under age ?

If so he IMO would definitely lose interest otherwise I can see someone waiting

Really? I would say if she's important to u than anything else in the world. Then 3 years is worth the wait. If she's not, then don't bother. Don't u ever see in movies that male character will wait dumbly for the return of female characters? Some are tragic... it's up to u to decide