Do you look at it 'from above'? Then your descision will probably be easy. You have an idea of what a relationship should be, and all you need to know is wether or not it applies. If it doesn't suffice, then a break up is inevitable.
Do you look at it 'from your own point of view in terms of environment/habitat/future/integrity, etc.' Then comparing all the aspects in a before/after fashion may result in some negative outcomes. A break up might be prefered on some points, but the chances of losing out in other aspects could not be worth the descision.
I do the first and deal with the conscequences as they come. You seem to favor the second. Neither can be said to be the best course of action as it is situational. Though it is true that my way might be more risky, double or nothing kind of bet. While yours is a more balanced win some or lose some bet.
Obviously, I am extremely Ti-rigid. I have had a moment in my life where I forced myself to rebuild my entire way of thinking, because I was unable to deal with some situations. I have moved my perspective.