FRANKENSTEIN: There can be no wedding while this horrible creation of mine is still alive. I made him with these hands, and with these hands I will destroy him. I must find him. [to Victor] You stay here and look after Elizabeth. I leave her in your care, whatever happens. Do you understand? In your care.
In the original version of the film, Henry dies, and Victor ends up with Elizabeth. So this is the moment where Henry hands Elizabeth over to his rival. You might think, hey, Frankenstein, you jerk: you don't get to decide who she marries. But Frankenstein isn't going to listen to you.
Remember, the whole film is about him trying to create life by resurrecting dead bodies, rather than by just getting married and having a kid. He wants to control stuff, especially stuff having to do with women, like birth and marriage. Really, it's hard to know what Elizabeth sees in him.