I really don't care for the hate the OG party is getting they seem like nice people (or most). In the first chapter Reynold (the shield guy) kept checking up on him to make sure he was okay, he tried to stick up for him saying he "-just can't use his abilities yet." and not to let it get to him...
Correct, this isn't true NTR, this is some odd story script NTR variant where a character that was meant to join up with the hero but was stolen away by the villain (stolen in "the actions of the hero and the villain causes a change in the plot" kinda stolen, MC did nothing wrong).
I've been really enjoying the return to fluff vibe the last dozen or so chapters have had, here is hoping it keeps going and the author doesn't feel the need to insert another bloated drama arc into the story.