I don't quite get who you are avoiding cheating on?
I am coming around to the belief that monogamy may be as hard-wired into some of us as polyamory is into others. Maybe that hard-wiring is deeply buried and is only recognisable after we've cleared out a lot of mess and rubbish from previous toxic relationships. Like you I wasn't like this when I was younger.
Polyamory has always made sense to me intellectually. When I started out on this board I was very open to the idea that monogamy was a cultural norm and once personal defects of jealousy and insecurity were dealt with it would kind of fade away and be replaced by this wonderful compersion and ability to love freely.
That hasn't happened for me. Yes I dealt with jealousy and insecurity and I want my partner to experience his polyamorous self. But I think I also need to experience my monogamous self and I don't know if that is truly possible with a polyamorous partner. This realisation has taken a long time to surface and I'm not ending my relationship but it is a new paradigm for me and I will have to see where it goes.