Although, in Jacob's defense, there are clearly wolves who have never imprinted, as they thought prior to this pack that imprinting was a rare exception. Even then, as yet, Seth and Leah, Embry, Collin and Brady have not imprinted. I guess there's still time for all of them, though.
So it can be assumed that those wolves who didn't imprint married whoever they fell in love with naturally. This is pretty much what Jacob tells Leah. What's wrong with just falling in love the normal way? So it's not a foregone conclusion that any of them will imprint, and since Jacob was in love with Bella, why not try and save her for him, especially if he thinks she feels the same way but is denying those feelings? There is an argument for him going the way he did, but anyone with a good dose of decency would probably have not gone as far as he did, or at least, gone about it a different way.