How to negotiate boundaries?

Hello to everybody. I'm new in this phorum and I'm so thankful to find this resource.

I would like to ask you comments about my questions. First I introduce myself and my situation.

I have a friend with ADH, I know him since I was 15, now I'm 29 and I can say he is my best friend since then. Now our situation has changed, we're partners. And.... ok some issues have appeared in this new panorama, more of them you have commented in this phorum.

One thing I have clear, that all love relationships require a 100% of yourself to be in a great way, but with ADH you need to be 200%, and it's not bad, because you're at first being more wonderful person.

We have different troubles, but at the same time we want to overcome them. But now I have a trouble with him and myself and this is the following:

Since now he had a good attitude to improve many things, and I admire him. But since we had a little problem with sex he has changed his attitude. He wants to be fine, but he doesn't. He has a frustation, but instead of continuing to be in good attitude to overcome this, he now is more cold, distance and this hurts me so much. Because his cold provocate my sadness. I have also my history, and partners without ADHD have also our internal problems, we're not perfect. And for me to manage his coldness is difficult, because I can work fine with this feeling between us. I know he loves me so much, but now I have this crisis in front of me.

I don't know if I can negotiate some boundaries, because I know also that he wants, he can change his attitute, he demostrated this during more of 14 years. I'm scared, because I don't know if I'm ready to manage these changes, some weeks he is the best sweety man that I know, and others he is a cold man. When he is in this way I feel as a little baby, and this not contribute to be ok.

My question is if to negotiate that some breaks in our relationship when this period of cold is between us is ok or not. Because I think that we need to be separate in this period. To tell him that I can't manage his cold it's ok?

I don't know which is the solution, but your contributions are welcome.