I totally agree with what you said about karma. Sadly, things
are taken lightly by too many people these days.
Those who are attached will still flirt, because they're not
married yet...
Those who are engaged think nothing of flirting either, because
they're not legally married yet...
Those who are married, find excuses for flirting and/or having
affairs like, their spouse doesn't understand them, they feel so
alone, they no longer communicate, yada-yada...
And, yes, what comes round does go round. Deliberately break
someone's heart? Ah, let's just wait for poetic justice to come
round! 
Sorry... I'm totally intolerant of infidelity and unfaithfulness.
Some people think it's kewl that they can string along a whole
cheem gang of admirers, or set a whole gang of men howling like
hyenas as they swagger past in their skimpy clothes, but I think
that's so trashy! 