It appears to me that dating and dieting have some similarities:
Both require impulse control.
Both have short-term pleasure traps with long-term consequences.
There is a responsible behavior for both, that is difficult in the short term, but pays off long term:
Eating healthy food may not be as much fun as eating candy but will keep you healthy. Dating someone you are not fully attracted to, but is objectively a good person will have more long term positive effects, than dating someone who you are fully attracted to, but who leaves after a few nights.

I don't think it's ok to have a cheat day while dating, but I hope you get the broader point I am trying to make.
Feel free to disagree.

To me, people that sleep around are similar to obese people. For a small group there is a health/psychological reason, but for most it's just a lack of responsibility and impulse control.