I've known someone my entire life who does that.

I eventually concluded it is more to prove he is smart than anything else.

I see two or three parts to the contradicting habit

1, 2. You are wrong
(I know what you are saying and also that it is wrong, so I know twice as much as you do)

3. (optional)
   and I know the opposite is right - (I know three times as much about this as you thought)

Sometimes the person who has to constantly prove you wrong does so because they were constantly told by someone else in their past (parent ? teachers ? significant others ?) that they were wrong about pretty much everything. At some point they begin to believe that they can only validate themselves by diminishing you. Its easy enough to just disregard people like that unless they are your spouse or significant other - or your boss - in which case you have some decisions to make. Your last sentence is insightful....

people who are never wrong are liars. Mark my word.

I lived that for far too long.

Every so often, you just gotta book.

Thanks for everyone's responses so far. I should say that this person is / was a business partner. ( (Although, at the end of my marriage, my ex wife was carrying on similarly, but not as extreme. )

Although these relationships have ended, just recently, looking back have I gained this new perspective.

Arguing and contradicting a partner is a female trait. Women are typically in charge of hetero relationships, so want to keep the upper hand. In fact, a famous study shows that the only relationships that succeed long-term are those where the man yields to his wife.

But that sounds like many of the people on this website. Not surprising, since creative, high IQ people are frequently androgyne, even they don't know it. It doesn't matter what I say, or how commonly certain things are known, someone will pop up to contradict and challenge me, declaring "fake news!" It's so annoying that I've almost reached the conclusion that dating someone high IQ is more annoying than it's worth. Better to have a less intelligent, but nice person.

Your last couple sentences sum it up nicely. Not a healthy relationship.

I have been in a relationship that deteriorated to exactly that point. I am not sure how it got to there, but I couldn't say it any better than you did: "Obviously it's hurtful. It's definitely a sign that the relationship is twisted and not healthy. It's a lot of things none of them good."

A good relationship is kind, forgiving, compromising... sometimes there is enough of a buildup that a break is needed whether due to stress or whatever it may be. Distance (a break) helps gain perspective. Hopefully that’s all that’s needed in case it was once a loving relationship? Quiet time to help reflect on what’s important and sort out the feelings one is bombarded with. But ultimately the biggest reason any kind of relationship breaks down is communication. When it gets to this level of opposition my experience with something similar is that when stress levels rise, how one deals with it, especially if overwhelmed by the stress, may be unhealthy and ultimately the shrapnel may hit a close target. Show that you care and are there if/when they need. Maybe the other person just needs time to figure and sort things out?

This isn't a healthy relationship. Competition and control have no place in a relationship, especially a romantic one.

Some people would rather be right than be kind. Winning at all cost is not winning. The question Ann Landers used to ask was: Are you better off with them or without them?

A couple that doesn't have to prove each other wrong makes a healthy relationship.

That is a sign of discontent. The person is trying to push you away for some reason. Believe me, I know this ploy. He/she is unhappy and wants to put psychic distance between the two of you.