As well as the OP knows or thinks they know the people, You never really know what they are really thinking. Does the Girl want to become more yeshivish or does the boy want to become more modern, you really dont know that. If there is something there compromises can be made.
As far as the wife taking the husbands minhagim, Not all Minghagim are worth fighting over, I mean is it really worth fighting over the exact amount of a Kezayis (Ive seen arguments over this) . Many couples do make compromises on this as well especially if the husband is closer to the wife’s family