See saw, I don't know if you meant it this way but that really came out as odd. When I first read it, I saw it as though you were saying in general if someone wants to be monogamous that they need a theraptist because it's odd lol. After I thought about it, I think I get what you meant :

If you wish to be monogamous but find yourself having a hard time doing so, then you need to find a therapist to figure out why and what to do about the problem.