Yes you can avoid the NTR.Since there is no Dev's note or post about it I take the liberty of asking this question, is the ntr optional?
If I had to guess based on the overview, if the MC pays he keeps the girls, and if he doesn't the girls pay for him. Or it will happen no matter what?
NTR happens as a consequence of Ryan failing to live up to being the man of the house. If he can pay the weekly mafia dept Jacky has to strip to pay it. If Ryan doesn't help Lauren win the election Matt wins and NTR ensues.
I wouldn't say there is any grind in the game, by the time Sidney starts working at the club you're making more passive money than you can spend.