following the halacha cannot cause shalom bayis problems.
That’s not true.
Following halacha can cause shalom bayis problems if both husband and wife aren’t on the same page. Especially if one wants to keep halacha and one doesn’t.
Transgressing halacha may not cause shalom bayis problems if both are on the same page. For example, if both husabnd and wife decide to hit McDonald’s for a cheeseburger, it wouldn’t cause shalom bayis issues.