To answer the original question, If it’s in ruchnius,
I think the parents have a right to object,
& the child should respect their wishes.
However if it’s in Gashmiyus, & or Shtusim, then the child
has no obligation to listen & should RESPECTFULLY do what
he feels is right.
One should tell them respecfully, that ultimately he/her is the on who will
live with her/him & it’s his choice.
Unless (in my humble opinion) he is Somuch Al Shulchan Oviv,
then if they support him/her they should have a say.