Even if you respect your partner's intellect and are initially attracted to their mind, over time, you'll find yourself trying to best them in every conversation. They'll pose an opinion, and you'll counter it -- even if you secretly agree. They'll assert a thought and you'll either disagree or add a clarification, just to have the last word.
You'll criticize their ideas, either blatantly, through sarcasm and pointed jokes, or through frequent low-grade disagreement, in effect rarely letting them speak openly and have their ideas simply accepted. Where will this urge come from? In another lifetime, either you were this person's teacher or mentor and you used tactics such as criticism and sarcasm to teach them to be sharper in their thinking; or you were actually subjected to this same kind of treatment yourself, as this person's student. Either way, you learned these tactics to demonstrate intellectual superiority, and now, in this life, you'll use them again to show your partner you're always a step ahead. The problem is, you won't always be a step ahead. Categorical disagreement means you won't listen to what they're really saying; rather, you'll listen for the cracks in their logic, the flaws in their thinking that you can exploit. But in failing to listen carefully, you'll miss the details, not to mention the emotional content. Plus, your partner could become quite reticent about telling you what they really think or feel about anything, because why should they bother when you'll just shoot their ideas down? If you want this relationship to be a healthy, mutually satisfying growing experience for both of you, you'll have to learn to quell your urge to have the last word and always be a step ahead of your partner intellectually. Take a more humble view: You have as much to learn from them as they have to learn from you, if not more.