if the relationship doesn't have any flaws, then you can't budge in even if you're brave enough. if the girl/guy in the relationship has enough love, then sluts & man-whores will not be able to get on the ride
true.
but people still accept the 第三者. break ups/hook ups don't need a reason, some might give a reason, but they can also choose to use an excuse. that's how this world runs.