"The only true voyage of discovery would be...to behold the universe through the eyes of another." ~ Marcel Proust
In grad school, when I first started seeing clients, I found it hard to be nonjudgmental. Naturally, the more judgmental I was, the less effective I was as a therapist. A supervisor helped me with this by pointing out that most people are trying their best to get through life. Not many people wake up and say, "I'm going to do my best to really screw this one up." Her challenge to me was this: every time I found myself being judgmental, try instead to be curious - to figure out how whatever that person is doing made sense given their unique situation. That has proven to be one of my life's most powerful lessons. I've since come to believe that the failure to see a situation through the "other's" eyes (be that your spouse, partner, boss, opposing political party, or whatever) is a huge part of failed relationships. How quickly we can rush to a judgmental response (almost always one that justifies our actions and minimizes theirs) rather than truly listen. And when it is hardest to listen is when it is needed the most.
So give it a shot. Think of a relationship in which you're stuck. Do you truly understand them? How do their actions, beliefs, etc. make sense given where they are? How might the relationship change if you met that person with compassion rather than judgment?
I should add that meeting someone with compassion and curiosity doesn't mean you have to be a doormat. It doesn't mean you're weak. Quite the opposite, actually; it requires a lot of strength. And you don't have to agree with them once you understand them. You may even choose to not associate with them anymore. It's simply a peaceful way to live.