So... to those people saying "NTR, thus I hate" the situation as presented here is... emotionally a lot more messy than that.
A kinda-sorta breakup putting the relationship between the existing couple in "it's complicated territory" combined with the lead character initially just offering a place to stay, this feels like a fairly organic setup that can actually happen in the real world, and doesn't carry the same kind of moral weight as cheating, or the uncomfortable lurid fetishization of the "cuck chair".