My DS's girlfriend has been accepted into a very prestigious (and very expensive) post graduate program in New York City. Housing costs there are astronomical. My DS plans to spend the year there with her. He asked me today if I would cosign for their accommodation. I'm not sure yet what that would be but it is separate from the University as they have limited school housing. I would normally tell someone to say no but she may not be able to go if she can't find a place to live.
AIBU to say no?