Sacrificinh love

In almost every serial heroine backs off because other parallel female lead is weak and needs to get married to male lead

And vice versa

But it's not like job or non living thing or property that can be easily transferred and it won't ever came back to you

But with humans if they are attached to someone else how can you stop your heart or someone else heart to stop feeling the emotions

Yes may be they can marry someone else but their heart will always long for someone else and seeing them near like being SIL or BIL one can never get over

Back of the mind they will keep thinking about getting back to their first love

And real world either they cheat or leave their spouses

So in the long run it will hurt all of them or atleast one of them

So how it is useful

Never got this logic of ITv serials

Confusion is one thing, family reputation one thing but marriage is life long commitment