oy vey... does he feel the same about her? It does sound unhealthy... like he'd have the potential to either control her pretty severely or feel so suffocated he'd dump her and find someone else... and who knows what that would do to her mindset? Mind require a bit of counselling, but she has to realize she needs it first. Sometimes people get so caught up in what they thik they want to do that they won't listen to wisdom from others.
Heck, if I otherwise liked the name, I would be ok with naming a child what I liked even if it was the name of a past romance of my own partner (maybe easier if he were a widower and that was a chance to honour the guy's first wife)if it was one that he had liked before he even met the other person.