Resentment is a big issue that, earlier in my career, I really didn't know how to tackle.
Here's what I've learned from my years of working with couples, many of whom have underlying resentment that lives under the surface and pulls the strings on their interactions. Often, resentment is present when connection is not. Often, when connection is ADDED... resentment gets smaller, sometimes disappearing altogether. Until, of course, that connection falls away, at which point the resentment easily pops back up.
Resentment and connection are 2 sides of the same coin.
Anytime you feel resentment, either from yourself or your partner, don't try to get rid of it. Just increase connection - ASAP.
If you want to resentment-proof your relationship, if you want to learn how to deal with the resentment that is there and it's there for good reason - focus on increasing your connection FIRST.
Once there's safety and trust built from that increased connection, you'll be able to talk about the resentment, to give it a voice, and to honour it - it's there for a reason.
But that deeper work can only happen once you've built a solid foundation of connection, of trust and safety, of feeling truly important and valued in your relationship.