If you wouldn't do it or even considering doing it why would you even ask the question?
It doesn't really matter if you can do it or not, if someone is with someone it's really not your place to try and stop them from doing what they want.
If you have any morals for that anyway.
Either way you can't make someone not be with someone. If you really have no form of life and hate it that much then you can influence them not to be with them.
Stay away from spells on this one.