I think its about not being able to choose. And not being able to choose can have several reasons.
You don't want to hurt the one you love right. But one of them is going to get hurt.
Maybe your afraid that when you finally choose, hurt the other one and after some time..Damn...wrong one and your left behind. Alone.
Maybe it's being afraid to tell the other because you know he or she is going true hell.
There can be many reasons but personally I don't think that we can love 100% two persons at the same time...It would not work...
