It is not possible to be happy at the expense of someone else happiness. Love does not destroy, creates.
It is just their little twisted minds that are confusing everything. They think happiness is material things, flashy toys and new OW and that love is the high and rush of in-fatuation.
They are deluded. Just like any addicted or person with and unbalanced brain. They see a fantasy and think it is real.
Sometimes good things fall apart so better things can fall together. (Marilyn Monroe)