In our culture, before the love of animals replaced the love of humans, we used to say that you could tell how your husband would treat you based on how he treated him mom and sisters. Likewise, you could tell if a woman would be trustworthy based on her interaction with the men in her family.
Now we go by the direction of animals. I would still stick with the human to human interaction as a guidepost in observing a lover.
I watch how they treat the hired help. Getting condescending and crappy with people who aren't really, really, asking for it is a definite deal-breaker.