Years of observing dog behavior help me know which dogs are likely to get along and who will not. Yet after fifteen years, there is no definitive rules that are one hundred percent true.
Daily we meet people who confuse, challenge and delight us (sometimes all that in one person!). Sometimes we are nothing but nice to a person and they still choose to reject us, slander us, and are generally sneaky and unpleasant.
Instead of taking it personally, we must recognize that it that person's issue, and not ours. When I find I am starting to really dislike a person, I try to remember to ask God to give me eyes to see that person the way He does. Sometimes that prayer is answered in ways that allow me to see that person's brokenness, which heals the anger I may feel toward them. Other times, not much changes except the intensity of my emotion.
People and dogs - just when you think you've got them figured out, you don't. But that's not all bad. Life's mysteries make every day living interesting. God created a diverse and wondrous variety of beings. And we are one of them.