As I see it, it does make you an unqualified POS.
The marriage vow is made not just between man / woman, but between man / woman / family / community / God. in light of this broad and unqualified commitment, a unique relationship is sanctioned, and breaking it entitles you to the scorn of your spouse, family, community, and God.
And, as some have noted, cheating on your spouse does not arise out of the blue. You worked at it, formulating a relationship the culminated in infidelity. It isn't a one-time mistake, but a pursuit mindfully continued without regard for your vows.
It's been years, but I still harbor resentment to an ex-brother-in-law that was unfaithful to my sister. I love my niece and nephew, but I can't forgive him for the callous torment he caused my sister.
Hey, it's just my opinion, but yeah, if you cheat, you are a POS.