63 year old woman here. Husband is a few years younger but not wildly interested. He always had a somewhat lower sex drive than me and I think would not bother if I hadn't made it clear it is important to me.
I think as you get older it's easy to let stressful patches, minor illnesses, joint and back pain etc. get in the way, then suddenly you realise it's been months. At that point you can let it go, or tackle it head on. I don't want to live in a sexless marriage so I've made sure we had the difficult conversations, and I'm glad we have. We now have sex every few weeks to a month or so and we do both need to be relaxed and not exhausted.
I'm pretty sure he's not using porn or seeing anyone else. He has mild ED and the best way for him to come is through masturbation, which takes a long time and is frankly bloody hard work. We have adapted and he will now finish himself off, which I don't mind at all.
It does matter to me but I can live with it being occasional. I do need orgasms but can do that for myself in between. We have an excellent relationship on the whole with a lot of affectionate touch, so I'm not at all interested in looking elsewhere.
I've pondered having a regular date night where we go to bed a bit early knowing we are going to have sex and see how it goes. We're having sex often enough that hasn't felt necessary. But I think it can be a habit you get out of and making a commitment to have a go regularly can work for some.
Emily Nagasoki's book "Come Together" is very interesting on sex and ageing. She talks about the difference between desire and pleasure. At the start of a relationship, desire is high and sex often happens easily and spontaneously. When that changes with age, we try to rekindle the spark - but actually, if you put pleasure, not desire, at the hart of the relationship, you can basically commit to exploring what feels nice and seeing where it goes. It might require some organising or pushing through embarrassment, but it does offer an alternative road map for a continuing and satisfying sexual relationship.
But - if it doesn't bother you or your partner, it seems to me it's 100% fine to let that part of the relationship go, as many women on here are describing.