Navy, above all else, wants to be an aunt. Not necessarily a mother, but an aunt.

Why?

Well, if she's an aunt, and she has to look after her niece/nephew, when the child starts crying, she can always calm him/her down by saying, "It's alright. Mum and Dad will be back soon."

However, if she is the mother of the child, this response does not work so well.

Navy will open her mouth to say these words, realise that she is actually the mother and freak out.

(This is kind of what happened for the majority of Félix's babyhood)