Swinging is not NTR, though the protagonist does get uncomfortable at first and you've got plenty of opportunities to chicken out if you're too insecure about your relationship with your girl
I'm very pleased this game is approaching the stag & vixen lifestyle, too few games ever cover this. You can be a dominant man with a slutty girl and decide whom her bulls/bucks will be. As things stand, I'm hoping to include Rachel and Tyra at some point - maybe a twisted filthy path where they try to tempt the MC away from the daughter, causing her to embrace her inner slut with other men out of jealousy or spite. No happy ending here, but lots of depraved sex for both the daughter and the MC