He's not paid to be a lover!
The relation builds up; money is just the way it's bridged since he's broke.
Lets just cut the crap. The real life "sugar babies" website? Sugar daddies, sugar mommies. Its nothing more than legalized prostitution. You can tap dance with your word games. But at the end of the day? Older person with abundant cash, younger person willing to put out for financial gain. The mommy/daddy, is the JOHN. And the sugar baby? Is the prostitute. Get over it, its just what it is.
That's not to say your idea is all bad. Harem, sells reads. First choice. Is the harem the guys, under one good looking rich MILF. Or, is the harem all the sugar mommies he prostitutes himself out to. With a harem of sugar mommies, your MC is a whore, plain and simple. A reverse harem of slave boys? Can you say *cringe*.
Make it one sugar mommy, a MILF mommy dommy. Sweet mommy or strict mommy, your choice there. NOW you have a relationship. Not a sale of sex. You can explore the relationship. Not sure how much yu can &explore& it on RR though, what are their rules on content. You might have a lot of "implied" action. And that complicates your gooner factor, which is your target audience. You can all it a "dark romance". Actually a reverse dark romance. Problem there is, women like romance, men like something different.
Yet, you have something to play with. (and so does the 37 year old MILF, in your story) lol.