Similarity leads to attraction for a variety of reasons. For one, similarity makes things easier. You can imagine that if you only liked to go to action movies but your partner only liked to go to foreign films, this would create difficulties in choosing an evening activity. Things would be even more problematic if the dissimilarity involved something even more important, such as your attitudes toward the relationship itself. Perhaps you want to have sex but your partner doesn’t, or perhaps your partner wants to get married but you don’t. These dissimilarities are going to create real problems. Romantic relationships in which the partners hold different religious and political orientations or different attitudes toward important issues such as premarital sex, marriage, and child rearing are of course not impossible—but they are more complicated and take more effort to maintain.
In addition to being easier, relationships with those who are similar to us are also reinforcing. Imagine you are going to a movie with your very best friend. The movie begins, and you realize that you are starting to like it a lot. At this point, you might look over at your friend and wonder how she is reacting to it. One of the great benefits of sharing beliefs and values with others is that those others tend to react the same way to events as you do. Wouldn’t it be painful if every time you liked a movie, your best friend hated it, and every time your friend liked it, you hated it? But you probably don’t need to worry too much about this, because your friend is probably your friend in good part because he or she likes the same things you like. Odds are that if you like the movie, your friend will too, and because he or she does, you can feel good about yourself and about your opinions of what makes a good movie. Sharing our values with others and having others share their values with us help us validate the worthiness of our self-concepts. Finding similarities with another makes us feel good and makes us feel that the other person will reciprocate our liking for them (Singh, Yeo, Lin, & Tan, 2007).