Right, it sounds to me like the relationship with your current bf isn't so strong if your mind is wandering like this... but obviously you care about him too much to dump for the college-guy [shall refer to them as BF and CG now
].
So, I'd recommend that you genuinely find out if CG is more than just a fling. You need to make sure he's really interested, and there's a future [obviously not for life, but still.] before you commit.
If you have more in common with CG and you're having doubts like this, I think the relationship with BF isn't for you, however hard you might find it to end it.