I'm not ignoring suggestions just yet, just saw a post that resonated with me and made this up in a few hours.

Anyway title does the heavy lifting as well as the intro text, your girlfriend has an very well preforming but abusive and strict boss who for unknown reasons stole your body and life. Now the woman you love is trying to come to terms that the person she loves the most now has the body of the person that she hates and flinches around the most. Doomed Yuri my beloved, I did it make so that Sarah (the girlfriend) is Bi and has a jealous crush on the boss's body. But it's up to you if you want to try and erase the Boss's persona to remind her of the real you, maybe get some revenge by ruining Mina's brand, or maybe the high heels and domineering attitude might be the way forward?

Boss = Mina Fairfax, GF = Sarah Jenkins.
Appearance wise, Mina has the appearance of Zani from Wuthering Waves and Sarah is Arlecchino from Genshin Impact. Why di look like that but not them inherently? Because I think the image nails the premise really well and I don't believe in false advertisement as a concept. Also Zani and Arlecchino are hot.

Intro texts are the same but -1 paragraph moving down to make your own stuff. I'm aware that JLLM might clash persona description with Mina's appearance body so I'd at least keep that in if you make your own. I tried to make Sarah monotone and distant around {{user}} but trying to maintain the attraction, longing and fear makes it a bit of a mess so always edit to your hearts content.