There is a gentleness in being around people you love who love you. When profoundly content, self-regulation can soften.
This can mean we treat those we love worse: we relax our guard, and our inner asshole makes an appearance. This is all the more reason to work through your issues so you can relax when you relax.
Equally, when surrounded by loved ones without the need for competitive rivalry, we can drop politeness, sycophancy, or bitterness. Without mediating or acting out, we might slip into our best self.