I want to ignore my gf
Is there a reason for this?
Because I want to find out if she can still be by herself without me
It is understandable that you want your partner to be independent but ignoring them is not the way to go. They will get confused and hurt and it could damage your relationship.
Nah, I'm feeling good without her.
It is rude to ignore your partner. She might feel hurt if you don't tell her the reason why you are doing what you do.