Generally speaking, romantic relationships form around common interests, compatible personality traits, or similar beliefs and values. But none of that compares to the love connection that can be formed by using basic words like "he" or "and" together.
Pronouns ("he", "them", "you"), along with articles ("the", "a", "an") and conjunctions ("and", "but", "or") are among the most basic and most widely used words in the English language. Collectively referred to as "function words", these words are so simple and well understood that most people don't actively process them when understanding sentences - instead, our brains process them quickly and unconsciously.
That's why these function words can have surprising power in forging relationships, at least according to research by University of Texas psychologist James Pennebaker. He studied 40 men and 40 women who were placed in a speed-dating environment and asked to talk to a dozen strangers of the opposite sex for four minutes. Afterwards, the participants were asked to rate the twelve meetings based on how well they thought they went.
Pennebaker then analyzed how often and in what combinations various function words were used in the conversations. He found that the conversations were these words were used in similar frequencies tended to be the most successful, suggesting similar use of these function words helps make for a better relationship. He found similar results when he analyzed 86 couples, finding the overlap in function word usage was a key predictor of whether the pairing would still be together after three months.
There are a couple possible ways to interpret this - it might mean that we're subconsciously attracted to people who talk like us, but Pennebaker favors a different explanation. He thinks that this is really a sign that the most successful couples are those that adjust their use of function words to match each other, because that's indicative of people who are really listening to each other, but consciously and unconsciously.