I like this quote about honesty in relationships the best and I believe it sums up everything else. I read this in Today in the Word on March 28, 1993.
During his time as a rancher, Theodore Roosevelt and one of his cowpunchers lassoed a maverick steer, lit a fire, and prepared the branding irons. The part of the range they were on was claimed by Gregor Lang, one of Roosevelt’s neighbors. According to the cattleman’s rule, the steer therefore belonged to Lang. As his cowboy applied the brand, Roosevelt said, “Wait, it should be Lang’s brand.”
“That’s all right, boss,” said the cowboy.
“But you’re putting on my brand,” Roosevelt said.
“That’s right,” said the man.
“Drop that iron,” Roosevelt demanded, “and get back to the ranch and get out. I don’t need you anymore. A man who will steal for me will steal from me.”
If the person you are with will extremely negative about their ex then when or if you break up they will do the same to you. If the disrespect others whom they care for when no one is looking they will do the same to you. Remove double-sided people from your life and put yourself at ease.