It’s been a long, hard day at work. You want to come home and just relax and have fun with your kids. You don’t want to deal with discipline. But Mom has had the children for most of the day and she’s tired of the fighting and bickering. So she starts to discipline and wants you to help. This is not your idea of unwinding.
So what do you do? Support her. Absolutely. Children need a unified front from parents, and when Dad is viewed as the Softie, it makes Mom look like the Bad Guy and makes her job so much more difficult. And marital tension increases dramatically. If you have an issue with the way Mom is disciplining, wait to talk to her about it after the children go to bed.
Short term, backing up your wife will be extra work. But long term it will be well worth it as your children will be unable to pit Mom and Dad against each other. The softer you are on discipline now, the harder it will be for your family.