For a woman in a new lover-style relationship, there's typically more than only sex that is driving her.
Typically it is going to be things like these:
There are more, these are just some examples.
But these are mutual/aligned benefits. The man gets to enjoy them with her. Just as he is accepting of her, she is accepting of him. A provider might expect her to act sexually inexperienced and behave more reserved; meanwhile, she will expect a provider to be responsible, dependable, and fairly respectful. With a lover, she can show her sexual experience and drop the reserve, and he doesn't have to worry about being responsible or dependable, and can freely be more irreverent.
At some point she will want commitment and to move toward children, right. At that point the lover will have to decide if he wants to mix in a degree of provision or if he doesn't. If he doesn't, she'll eventually leave.
As for me having a 30-year-old cutoff, yes, that's part of it.
Less physically attractive, higher expectations, more demands, more baggage. The older a woman gets, in my opinion, the lower the value of her goods yet the higher her asking price. I also have a moral concern, which stems from a relationship I had with a mid-30s woman when I was mid-20s. I watched her age while she was with me, with her angling for commitment and a family the whole time, while I continually told her maybe, but not right now (which was my feeling then). When we split, I realized I'd sucked up years of her life when she could've been seeking a man whose goals were aligned with hers. That's no problem if she's in her early-to-mid-20s, because she's still gaining dating experience and building her life. But a woman in her 30s does not have time to waste. Her looks fade more and more each passing year, and her fertility starts dropping rapidly once she's in her 30s. She really is on the clock, in a major way, and I don't want it on my conscience with another gal like that that I sucked up time she should've spent looking for her Prince Charming. There are plenty of twenties and late teens women available, and they don't have those considerations.
(there are some nice perks to older women... other men have already trained them to orgasm, they've trained them how to please men, the women are better conversationalists, they're less idealistic/more realistic, and they've often already passed through their sexual awakenings, so you don't have to manage any of that stuff. In that way, they require a lot less training and maintenance once in a relationship. The flip side is they're on the clock, and you are wasting their time if your goals aren't in alignment. They're also much harder to mold in a relationship, and come with more preset expectations about whom they want you to be and what they expect of you, which is less good if you are a less conventional kind of guy)
But anyway, that's me. Seems like older women are fine for many men, which I am happy for. Happy for those gals themselves and the guys who love them :)