Shalom bayit is a family at peace, as one unit. When leniencies in law are used to avoid intrafamily conflicts, customs and d'rabanan halachot can sometimes be overridden. But d'oraita halachot may not be violated. Consult a rabbi.
Situation
You want to go to minyan but your wife is overwhelmed with trying to feed several children and she asks you to help.
What To Do
You must miss minyan and help her since your wife's needs take precedence over your wish to pray with a minyan.
Note With shalom bayit problems between spouses, a rabbi should be consulted for details.
Note Once someone is married, his or her in-laws are part of his or her family and are included in shalom bayit rules.