A casual relationship may take different forms. It may be an ongoing relationship that is purely about sex and has no promise of anything more, says Ruth C. White, associate clinical professor at the School of Social Work at the University of Southern California. Sex needn't be part of the equation, of course. A couple may go on dates without having a physical relationship. Each partner may see other people at the same time. By definition, you cannot expect exclusivity from a casual relationship, but every situation is different. It is possible to have a relationship without commitment -- and with each partner uninvolved with anyone else.

There is evidence to suggest that men and women view casual sexual relationships in very different ways, White says. While both sexes want commitment, studies have shown it is more of a priority for women, who are also more likely to hope a casual relationship will become exclusive. There are also biological factors: women release oxytocin during sexual intercourse, which makes them want to bond. Men, on the other hand, release testosterone, which may lead to the urge to have sex with other women.

A casual relationship can develop naturally into something more serious without any discussion between the couple. Be aware of the telltale signs that you are becoming exclusive, says Glamour magazine. Meeting each partner's family and friends (without coercion) is a sign that you both have commitment in mind. Spending time at home instead of hitting bars is another indication that a more meaningful bond is forming. Another sign is that you begin to assume that you will spend weekends together. Probably the clearest sign that your no-strings relationship is becoming serious is if neither of you are dating other people.

If your other half is not showing interest in becoming exclusive but you want him to commit to a serious relationship, discuss it with him. If you want different things, it is unlikely to end well, particularly if you are more interested in a long-term partnership than he is. It is time to be bold, reveal your feelings and ask him for exclusivity. If he says no, move on and find someone who will give you what you deserve: security, love and commitment.