Why do nice guys always finish last?

• Relationship length: Studies have shown that for short-term, casual relationships, women value attractiveness in partners, regardless of altruism (a measure of people's concern for others). By contrast, for long-term relationships, exhibiting altruism increased men’s desirability, even if they were considered less attractive. 
• Age: Research suggests that as people get older, their relationships tend to get longer, and they shift from focusing on individual motivations to mutual benefits. One study found that short-term, casual relationships (about five months) were more common in adolescence, while long-term relationships (about 17 months) were more common in adulthood. Due to the nature of relationships in adolescence versus adulthood, the traits that are valued (attractiveness and altruism) may differ as well. 
• Biological drivers: Evolutionary theories aim to explain how biology or reproductive organs drive partner selection if the goal is to perpetuate the species (in other words, to make babies). Essentially, they claim that men are driven by attractiveness because they produce sperm and have the ability to mate with multiple partners. Since women produce relatively few eggs by comparison, they look for social and economic standing for security. Notably, these evolutionary theories fall short for a variety of reasons given that both men and women enjoy casual flings, relationships aren’t only driven by reproduction, and individuals can’t be reduced to their organs. 
• Cultural values: Social context theories propose that the major driver in partner selection is cultural values that weigh the value of characteristics such as being a nice guy. Culture probably has some impact on people’s actions and perceptions, but research has pointed to the limited use of this framework, as it's clear that many women and men express different desires for their relationships than those that are portrayed in popular media.

What does all this mean? The reality is that individuals are complex and chemistry between two people isn’t an exact formula determined by a number of common traits. Being a “nice guy” or a “bad boy” may be just one piece of the partner-finding puzzle. Also, simply being "nice" to someone doesn’t mean they will respond in the way you hope they will or that they owe you anything in return. While a connection might be sparked by an attraction to one or more traits, that alone isn't likely enough to sustain one. 

It’s easier said than done, but it may be helpful to try not to sweat what’s happened to you before. Even if people your age aren’t looking for a long-term relationship at the moment (and may not fully appreciate the value of niceness yet), it's good to know that this may change over time. Instead of comparing yourself to others and focusing on what they have, you might consider taking some time to look inward to better understand yourself. By focusing on building your self-confidence, you may feel more satisfied on your own and may find that your self-esteem is more attractive to a potential partner. 

Most people seek the partnership of someone who's receptive, caring, thoughtful, and considerate. These are traits that aren't just desirable in the abstract: possessing them may help two people forge a special bond between each other and may contribute to growing together. Above all, don’t give up hope. Just because you haven’t yet clicked with someone who appreciates you for who you are doesn’t mean you won’t come across this person in the future. Staying true to yourself makes it that much more likely that you’ll hit it off with someone for the long-term.