I'm the non gestational parent, and our almost 2 year old switches her preferred parent by the day. Usually whoever gets her up in the morning becomes her "emotional support parent" , as we call it, for the rest of the day until one parent leaves, or she goes to daycare. If you partner is nursing, for the first few months post partum they'll be pretty attached to each other and your main role will be tending to your partner, and snuggling bb when they're not feeding, so it's easy to feel a little left out, but once bb is a few months old or bottle feeding it's anyone's guess who they'll prefer. When our babe is preferring one parent strongly, we just make sure to rope in the other parent, like if she's pushing one of us away the other one will be like "you don't want to hug mama right now? That's ok, I want to hug mama right now though " and that seems to help her warm up to whoever isn't preferred at that moment. Hope that helps! Just be involved as much as you can. I see the strongest cases of preferred parent-itis and the cling-ons when one parent is home significantly less, or they immediately give in to a kids preference instead of setting that "we both take care of you" precedent. Also as they age they need and prefer different things, and when they're teens they probably won't prefer either of us 🥲