caring for my playgirl

ive been a doc for years but lately i've taken on this weird roleplay thing with my girlfriend. she asks me to take care of her like shes little, like when she comes over and wants me to tuck her in bed at night or read stories to her. its kinda odd because im not her parent and i dont want to mess up that dynamic but we both enjoy it. makes us closer somehow. also ive started dressing up a bit more formal around her too just to play into the care role. sometimes shes silly and acts real little, talks in this high pitch voice, wears pigtails and everything. its cute but i wonder if im crossing some line by playing along so much? ive talked to other friends who do similar stuff and they say it helps them feel safe but idk if that's just us or if there's something more clinical about it. anyone else out there doing this sorta thing and wanna talk abt it?