BP Totty, as far as I know, no person stays static. The core characterisitcs of a person can stay the same however we our personalities are constantly evolving, depending on the stimuli around us. In addition, believe me there are plenty of leibedige Chassidishe bochurim (some of them take it to the extreme, unfortunately)
If a person is so unflexible and can’t change to the good or for Sholom Bayis, then there is indeed a problem. But most men change (hopefully in a better way) after being married for awhile.