Obviously I can't speak for your DH, but I'd like to offer some perspective from the other side of things which I hope might help in some way.
For many years I struggled with vaginismus. If you don't know what that is, it is very painful sex, which sometimes made it impossible. This created many issues, including showing affection due to the many confidence issues it brought.
Every time we tried, I either couldn't do it at all, or screamed in pain and had to scream at him to stop. I can't tell you how much of a total failure this made me feel. Both as a woman, and a wife 😥. No matter how much DH said he understood, and was patient, it drove me even further into a form of depression about it. Every time we tried and same thing happened, my feelings of failure got worse and I got more upset. Even with visits to the gp and a therapist, nothing worked.
Eventually we just stopped trying as it gave the same result. By this time, I'd lost all interest in it as didn't want to let DH down again!) and failing yet again! I avoided affection for a while because there was no point as sometimes affection would lead to the bedroom and... well you know what would happen so I avoided it. Mynmood was also low because of it. It was a vicious cycle. One time DH and I went away for a night to a hotel while his mum babysat, and I loved the fact we stayed out until 2am and were too tired and drunk to do anything by time we got to the hotel as I was dreading it the whole night 😞. Not because I didn't want to have sex with him, but because I'd let him down again and end up ruining a good day and night by me getting.upset and him feeling disappointed.
Thankfully I found a solution, and although I still have it a little every now and then, sex is at least possible.
I wanted to give another perspective before you make any quick decisions about your marriage. Thankfully for my DH, I was open to therapy, however it sounds like your DH has taken your suggestion as you making an issue about something he currently can't do. He is in denial, and this is the first thing you need to sort out in order to go forward. If you can't get through to him to admit he has a problem and see a therapist with you, then I honestly don't know where you go from there. If he'd rather lose you than seek help then this is your biggest problem, not his issue itself.
Talk to him and tell him this is about him. Reinforce that it isn't about you missing sex or sex being the most important thing, etc, it's about you as a couple. Good luck!