Monogamy was safer, easier, and commonly accepted, therefore "right".
But was it for me? I was still finding myself interested in others. This undermined the monogamous relationship more out of the perception of being wrong in wanting both - so one had to diminish - and then the lies did the rest.
Breaking up with my boyfriend was the first altruistic move in that relationship, and, as far as I know, might have been the first one in my life.
At one point I realised that I was staying with him because he was a good alibi to keep suspicions on my actions at bay, and that the way I was treating him had damaged his confidence and was keeping him hooked in a toxic relationship that he did not have the strength to leave. The breakup itself was very drama-free. We both knew it was for the best.
What came next a little less so...
May the Frubble be with you.