So, is the problem all about him (her)? Are you also responsible? Can it be worked out? Will one of you need to quit or be reassigned, just to resolve things?
Sometimes people simply endure an unpleasant work relationship, toughing it out day after dreaded day. That’s not a good solution. Why suffer when you can make it better? Most of these conflicts can be improved if not completely resolved. It may or may not require a visit with mediator or professional counselor.