Yes, NTR is avoidable. The game is primarily NTS. There will be ways to get your wife to humiliate you during NTS encounters, but only if you want it. Or, at least this is my plan right now.
Not a problem. Thanks for the support! Also, not gonna matter much in the beginning, but later you are going to want to resist the Succubus and some other women as much as possible in order to fully avoid NTR.