Growth.

There was once two Caterpillars who hung from a tree in their cocoons. Every night they slept they hoped the next day they'd wake up as Butterflies. It did happen, only that one of them became a Butterfly.

The Caterpillar shockingly asked with a frown on its face, "You changed?"

..and the Butterfly looking surprised reluctantly answered, "Yeah...I...did.."

That's how people are, they expect you to be loyal to them even though you have a better option. However, there's one thing you should understand;

Your life is yours, not theirs to live..