I'm sorry for the vague title. My memory is likewise very vague.
This morning, I suddenly remembered a scene from an old Disney movie (I'm not 100% sure if it really was from Disney, but I'm very confident it was). I was a child at the time, so it has to be from before 2002.
In the scene, the female protagonist pleaded to a powerful character to save her boyfriend/love interest. I think it was her father, and they were under water (maybe in a vortex?).
Her father hated the boyfriend earlier, but now decided to help him. He kinda charged his staff/wand while putting on a very angry face and even crunching his teeth. The boyfriend was shown for a second, eyes and mouth opened wide in horror, as he expected the father to attack him. But instead, the father used his magic to lift the boyfriend up to safety.
I can't get King Triton of The Little Mermaid, his trident and Prince Eric out of my head. But I own a copy of the movie and fast-forwarded it and watched a few scenes, including the ending - I wasn't able to find that one. It has to be something else. I've also had a look at a list of all Disney movies, nothing else sounds familiar. There's also the sequel to The Little Mermaid and the TV series, but I'm sure I've seen neither.
I'm not sure if the characters were really the father and the boyfriend. But I do strongly remember the charging/funneling of the magic with a furious face, and the horrified look of the other character who was then actually saved by him.