I'm not quite your age, but rapidly approaching it! Amazing, isn't it, how after all these years, you simply wake up one day and realize, I became part of the older generation. When did that happen? It has some drawbacks, but for the most part, it's a good place to be.
I believe you will find that most couples in their 30's and early to mid 40's really have no interest in older couples, and who can really blame them. Frankly, I have no interests in them, either, in terms of play partners. Too much of a gulf between us in terms of interests, thoughts, experiences, etc. Younger people make great friends, tho'. Help to keep you young at heart. The other thing is that so many in those age groups have parents your age and for many, they just can't feel attracted to someone that they equate with parents. Same holds true for older folks, too, tho'. They just can't muster enthusiasm or attraction to someone the age of their own children.
Another thing that isn't often mentioned, but I believe is at the core of things is that younger people really want same/similar in terms of body types, physical fitness, etc., and there's nothing wrong with that, either. I don't want to be in the position of displaying my little saggy parts and lumps and bumps to someone that hasn't had the opportunity to experience those body changes. Younger people just don't have a fine appreciation for those types of things.
This wasn't your question, but...I think if you would focus your search on people in the 50-60 age group you might find lots of willing and eager partners out there. Birds of a feather tend to flock together although there are occasional exceptions. - EBF