It’s not often but I hear this occasionally from my partner. She is not in a rush to do something else, she’s just had enough of getting fucked.
She doesn’t seem to realize that the negative feelings of that phrase actually inhibit you from cumming.
A better line would be, “I’m feeling a bit dry. Would you mind releasing your load into me now?”
Now that phrase would trigger a quick finish
Have you told her how that phrasing affects you? She can’t change what she says if she doesn’t know it bothers you.
Also, have you talked to her about why she wants things to finish up? Being done fucking could be for several different reasons, and some of those could be addressed so she doesn’t want it to stop.
For my wife it’s because she gets sore if we go a while, and wants to finish before things start hurting, so I know it’s time to grab the vibe to push her over the edge (something like 80% of women struggle to orgasm from penetration alone).