You can't buy love but you can buy a good approximation
I feel like a tortoise among hares here, with my one SB story. A quick update on Mary. You can "Find All Posts" to see the earlier history.
Two of the main risks with SB that are not well mitigated by anonymity are overspending and emotional entanglement. I was over-budget for months, figuring she would quit me for the fourth time and that would end it. In the meantime, I'd make each date memorable. But Mary started to like me more, evidenced by frequent praise and increased eagerness to meet. Recently, I decided I could not afford her anymore, so we renegotiated our deal to put me back on budget. This was a breakthrough for me, though it does make our relationship less stable since I'm not going to get it for free.
I think we have the emotional risks contained, too. We've discussed that Mary will eventually leave for a younger, single man. While knowing me, she does go on dates (none have worked out, supposedly) and describes being swarmed by men when she's in a nightclub. So, this is a matter of time, and I would not be surprised if she has other lovers even though she says she does not. We agree to remain friends, though, in the end. However, I have my doubts about how that will work since we're unknown to each other's family, though no longer anonymous to each other. For now, I just plan each next date and don't think much about the future beyond the next date.