Orleander said:
excuse me? Please explain
Have the dignity to end the relationship
before you pick up a new one. Consider, please:
(1) If sex with person #2 was "spontaneous", and sex is so important to your relationships, then it seems your relationship with person #1 was faltering vitally.
(2) If sex with person #2 came about after a buildup, it seems your relationship with person #1 was faltering vitally.
In either case, the relationship is already in trouble. Failing to recognize that, while perhaps accidental, is indeed suggestive of a glitch in one's moral or ethical matrix.
Either way, the situation described in the topic post points to a potentially recurring glitch. The effects of that glitch will manifest diversely, and more severely over time. The sooner you figure out where that error is in the code, the sooner you can test a fix. The sooner the glitch is fixed, the sooner you can move on to other challenges. The short phrase is, "It's called learning," but things are never as simple as the short phrase implies. ("Easier said than done"?)
There is a third option, that you are a cold heart, but we need not dwell on that here and now. Such presumption can wait until circumstance warrants.