Dating someone with ADD/ADHD

So I'm 5 months in a relationship with a guy whom I love really much. He's an adorable person and we have a lot in common, the time we spend together is usually great and I enjoy most of it. I would really like this relationship to work, but there is one thing that drives me crazy. He's got ADHD and it affects our relationship to a great extent - there are times he's very attentive and sweet, finds time to chat with me no matter what, but then comes a time when he is completely absent, the cute smses stop, he is stressed out, feels distant and cold. During the attentive phase he realizes how his condition might affect us and seems to understand how I feel when he ignores me, however during the withdrawal phase he might get very irritated and blow up, if I even mention anything. It feels like an emotional rollercoaster - one week full of love and attention, next one - as if I'm banging my head against the wall. I don't want to look needy, especially after spending some amazing time together, cause this makes him feel like he can't do anything good enough, but the sudden change usually makes me very nervous and I appear more clingy than I normally am. I just wish there was some consistency.
I don't want to end the relationship and I'm willing to work on this, but how to understand him better and make him understand me as well? Not sure he realizes that it's not easy to just snap out of his attentiveness and be completely chill when it all ends, I'm just shrugging my shoulders and wondering "hey, where did all that go? Did I do something wrong?". Does he need medication? Should I just leave him alone? How to deal with it? (and no "dump him" comments please)

You aren't allowed to say "no dump him comments". When you post on a public forum, you will hear what people really think.

I believe that although there is certainly a portion of the population who is actually ADHD, the diagnosis is vastly overused (as is bipolar, etc). Still, if he actually DOES suffer from a medical condition to the degree that it negatively impacts his day to day life, then he needs to be medicated.

If he declines, then yes, I would dump him.

You can't change him. Dating is to find out if who you are with is going to make a good partner in a consistent and ongoing manner. He's shown you who he is and it isn't pretty.
What is missing in you that you would want someone like him?

He is whittling away at your self-respect and confidence one cold shoulder at a time. Surely you feel you deserve better then someone who devalues you like he has been doing?

Yeah, as the others have said, if "dump him" is what we think would be the best advice, then "dump him" is the advice we are going to give. Don't get me wrong, I'm not saying that to be rude. I understand if that may not be the advice you want to hear, but we wouldn't be giving good advice if we didn't give people our honest opinion.

Now, that said, I actually don't necessarily think "dump him" is the right action. Or at least, I cannot say that based just on what you've shared. As smarta$$ said, this country does have a problem with over-diagnosing and/or mis-diagnosing things. It is a real shame because you can't get the help you really need if doctors just want to throw a label on everything even if it doesn't really fit.

That said, though ADD/ADHD can be very over-diagnosed/mis-diagnosed, that doesn't mean there aren't people who legitimately DO suffer from it. If he actually is one of those people, then to some degree, he can't really control it. Of course, that also doesn't mean you should have to just accept it. Therapy can help, medication can help, but the bottom line is if he legitimately does suffer from it, then he needs to be doing SOMETHING to try to get help for it. That isn't to say it would be easy. It may take time and a lot of hard work, but he needs to at least be trying. That is as much for him as it is for you or anybody else in his life.

If he IS trying, then hopefully in time things will get better. Now, all that said, if he is honestly suffering from issues like that (some people fake/exaggerate stuff like that as an excuse to just be an A-hole) then you can't fault him for that. So, you shouldn't nag him, try to change him, etc. BUT... that also doesn't have to mean you are just okay with it. It CAN be very hard to be with somebody going through all that. If you CAN continue to be with him and support him, then I say do that. Having a loving partner on your side can be a big help in getting through things like that.

However, you are not wrong if it is just too much for you. That can be very difficult. If it starts to become where it is negatively affecting your own health and mental well-being, then that may be a sign that this situation just is not right for you. So, yeah, my advice is not necessarily "dump him." I can't know your situation well enough to know if that is the right choice. More, my advice is to care about yourself enough to dump him if that is what is best..... but also care about him enough to give him the chance to get through this. If he's trying to fight through this, then try to be his partner in this fight. If he's doing nothing to even try, then that is NOT okay to you, and it's really also not okay to himself. IF that is the case, he shouldn't just give up and believe there is nothing he can do, and certainly shouldn't expect you to be okay with it if he did.

Good luck to you either way. I sincerely hope it works out. Good luck to him as well. I have never suffered from ADD/ADHD, but I've been through enough crap in my life to know how hard it can be to dig yourself out of things that seem beyond your control. It cannot be easy, what he is going through, so I wish him all the strength in the world in fighting the good fight.