I learned more about living with someone, and loving them regardless of faults, from one of my dogs - the first dog I got as an adult.
She was a Boston Terrier who had been abused. As a result, she had 'issues'. She would attack with little to no warning if she felt threatened. At first, she was not safe for children to be around. If she had been any bigger, I would have had to put her down. She disliked men (so much so a lesbian household with no kids was pretty much her only adoption option). She had bad separation anxiety.
She was also one of the smartest dogs I've ever encountered. She had a huge personality that impacted everyone she interacted with (sometimes this was negative but usually not). She had the strongest will to live I've ever seen in anyone. She lived fiercely and well with a severe heart murmur and then cancer for years. She had a ridiculous sense of humor - she enjoyed mocking me. She grew to trust and love me and Beaker, and then my parents and Beaker's parents. After much mellowing, she tolerated another Boston Terrier who joined our family and later on, my current dog, a chihuahua.
She was hard and difficult to deal with. I spent much of my thirties learning to cope with her issues. I adored her and miss her every day - she's been gone 3 years. I learned more from my relationship with her than any other relationship - the exception being with Beaker.
So I get it, long story short.