One appropriate story could be that mom's boyfriend is really into gardening. He often spends time in the backyard with mom, teaching her about different plants and how to take care of them. They've created a beautiful flower bed together, and it has become a lovely place for the family to relax.
Mom's boyfriend could be an animal lover. He volunteers at the local animal shelter. He convinced mom to adopt a cute puppy from there. Now, the puppy has become a beloved part of the family. They take the puppy for walks together and it has brought a lot of joy and a sense of togetherness to their relationship.