Please help!!

[seeking]

wow this sounds really sad but it is really possible, although I wish it's not...

You probably want to figure it out as soon as possible as you are still young. And if it turns out bad, at least you haven't wasted too much time on an unhealthy relationship.

[Borg69]

Is he on any kind of medication? Usually the only guys whom turn down sex are either dead, or can't get an erection.

If your age isn't the issue as questioned above, then I would guess he's hiding the fact that he can't get it up anymore for some reason... psychological or otherwise.