What is reasonable here?

I've been married (my second, her third) for 13 years in May. We dated for 5 years while I paid off debts (the reason I divorced my first). Our sex life went from 2 or 3 times a week right before we married to 2 or 3 times a month immediately after (one time on our 2 week honeymoon in Hawaii). It gradually tapered to nothing for 7 years. I, unfortunately, turn to on-line videos to help me cope during those years. I guess it became a sex killing cycle. No sex to videos to no sex. In the past year we have attempted to start again, at 63and 64. So that has been 5 or 6 times in the last year. It has certainly made us feel closer and been emotionally satisfying and she reaches orgasm easily most of the time. But I don't. She tells me that I should be patient and that I have unreasonable expectations. I have to admit that I have started to think that I'll need to move on if I expect to ever have a decent sex life again. I really think once a week, maybe more, would be good for me even at my age. Today she, for some reason, ask me if I wanted someone else. I paused because, knowing her, having someone else would require divorce first (I did promise). She quickly asked if I was thinking about divorce. I was truthful...thinking. We spent all day shouting (well, just her) and arguing about what's wrong with me since things have been going good. I'll admit, a time or two it felt good when I thought I was being understood. But basically her stance is that everything is good and getting better. I agree that a lot is good (she despises my children, threats them OK, just gives me heartache) except for the sex. But I can't see that getting good. Maybe we could get to a couple of times a month but I can't even see that being passionate. Sex is important to me and I'm starting to feel like I don't have a lot of potentially passionate years left. I hate to give up a good companion but I actually have started imagining myself alone but still happy. Is she right when she says it's not possible for a man my age to find what I want in a sexual partner?

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