About Anti-depressants:

Yes, Antidepressant therapy is a viable option and may potentially by a life changing one. Your BF is obviously "ill" and illness demands treatment. I think that your first step is getting a clear perspective on your influence in this debacle -- such as where your responsibility ends and his begins -- before seeking treatment.

There are many reasons why your BF may not have found AD's helpful in the past:
1.) He may not have given a particular AD a long enough trial. AD's can take 4-6 weeks to begin seeing improvement, and then several weeks, maybe months, more to really get the full effect .
2.) The dose was not high enough. This can make the time it takes from beginning a medication to receiving the full benefit of it take even longer. Psychiatrists will often slowly increase the dose with the hope of hitting the lowest most effective dose.
3.) Patient Non-Compliance -- Also counts as quitting too early -- a lot of times individuals don't take then every day at the necessary time. Also, alcohol can often reverse the effects of ADs (They both alter the same moody brainy-bits aka Serotonin.)
3.) It wasn't the right stuff -- usually after one failed AD an individual will have the same chance of success with another. Sometimes a third is tried, and if that doesn't work, often two or more meds are needed to hit all the right targets or often another class entirely can be used for great results. (I have never done well on an AD, I am finally feeling better on a Mood Stabilizer.)
AD's are only 30% sucessful in terms of full remission, but there's about a 70% chance of either remission or what is known as response -- which is a 50% or more decrease in symptoms. Even if your BF only 'responds', that's still significantly closer towards leveling out the extreme dips and hopefully bringing to light his behaviors.

For me, I believe meds can be extremely helpful and are the solution for a lot of us. However, meds will do nothing without self awareness -- we need to be aware of what an illness does and doesn't do to us. Meds may change how you feel but they can't really change how you act or treat others.

I don't know how much better your BF can get with the mentality that he has. But meds are an option you both can explore and stick with together. If he agrees to take any route towards treatment, lavish him with the attention and affection he wants but for only doing the right thing -- complying with treatment, treating you the way you want to be treated, and fostering healthy habits, etc....