This author sure loves NTR...
This isn’t NTR (cheating/cuckold) though??
It’s just someone who finds comfort through an unhealthy way which is sex and it stems from his trauma being raped, being forced to sleep with his close friend like brothers, then getting used to it. Both Pilgyun and Nanmu loves each other but hadn’t established a relationship nor commitment yet. So no NTR.
I personally don’t like it with any of the ML or MC sleep with someone else but I can’t say they are cheating either unless they were in a relationship.
Ines istg
If this is her doing and she doesn't apologize to carcel for all the shit she puts him through...