Justify

Justify:To give or to be a good reason for.
Usage:
I can’t really justify taking another day off work.
It was the only thing that I could do - I don’t have to justify myself to anyone.

Excerpts from soaps, novels and films:

Bold and the beautiful

“Brooke: Phoebe is not a kid anymore, she’s 18 years old.

Ridge: Will you stop trying to justify this, Brooke.”