While similar to what you mentioned, this one follows a different established Slow-Burn-NTR-to-Payback genre, which was kind of popular from 2018 to 2022. I mention these years because most of these web novels were published during that time.
For example, there's another manga (adaptation of a 2018 WN) with a very similar theme featuring a scumbag Hero and a Shota MC. It began publication in 2022 but is still in the "Despair" stage, in fact, things are about to get worse for him. (This one isn't being translated.)
And while the format of "Hero steals sub-heroines from the MC, be by misunderstandings, brainwashing, a skill, or the sub-heroines being pieces of shit too, or something, then the main heroine appears, the payback arrives, the Hero gets messed up while the cheating sub-heroines end up in despair or dead." is common, it isn't the only one. (Or even the most popular one, as the "Betrayed by a Childhood Friend" is seriously popular)
Frankly, most of them are garbage lmao, the only reason why I feel some of them are getting adaptations is because publishers are trying to see how the manga industry react to them.