yeah... people who are honest, and people who are full of shit :D
i don't believe for a second that most of you would pay $2000 back to a cheating partner. that's just the proper objective and moral response for a bunch of people behind computer screens with no emotional attachment to the situation.
if i were in a traditional relationship (read: one where cheating is among the ultimate dealbreakers) and i was unfaithful, i certainly wouldn't have the arrogance to expect my partner to pay back any debts they owed me.
the bonds of trust have been broken, and as such, all bets are off.
paying him back is unquestionably the "right" thing to do, but in situations like these a different sense of personal justice tends to prevail. welcome to the real world.