Well hon, adhd is a disorder that sometimes does require medication for someone to feel their best. Why is it headed in the right direction to leave it untreated? He may need to continue his medication in order to function at his job and in other ways. Side effects or not, his adhd needs to be under control.
some people take their medication during the week and not during the weekend or on vacation, etc.
But if he has primarily gone off his medication for you and the relationship because you like the 'real' him------- that is probably not what is best for him. Sadly, he may need it. Or is that sad? I don't know. Many people need medication for various things and just about all medication does have some side effects.
Maybe he's decided to stop the medication and you are just supporting him in his decision as HIS decision, and then I would encourage him to work with a psychiatrist in order to come up with coping mechanisms to worth through some of the functionality issues he is now facing.
Also, basic relationship advice here, we date for a reason. It is to judge whether or not to move a relationship to the next level and at times, to even continue it. We are supposed to be critical of what life would be like with someone and decide if we'd be happy with all of the complications any given particular person has.
One other thought is - really the meds should not be making him cranky, etc. Makes me wonder if he is on the wrong meds, or taking too much, or too little, etc.
If you don't mind - what was he on and how much was he taking?
I also wonder if he has had a decent physical lately with a good blood workup. I can think of a couple of other things that could be causing the lack of willpower, eating, etc. besides ADHD.
Hope this can help!