I've seen guys complain about it so many times on this sub that some girl made them wait for sex because she wanted something 'serious' with them while she had FWB or previous relationships where she had sex soon after meeting them.

Guys that complain about being 'made to wait' because some other guy hit it faster are acting entitled to sex. There is no way to summarize this frustration except with the core truth that they feel entitled to sex at the same pace as the other guys she previously slept with.

It is sex-entitlement, pure and simple.