This term is often used loosely, and there is some debate over what exactly constitutes a girlfriend. It is generally agreed that girlfriend status begins when two people agree to date. Getting a girl to agree to such an arrangement is considered a milestone for young males, and is also sometimes seen as a sign of status, based on the perceived quality of the girl. What the best strategies for getting women to agree to this arrangement are often varied and have been the topic of some discussion.

Partners in a non-marital relationship are also sometimes described instead as a significant other, partner or life partner especially if the two partners are living together. At times, since "girlfriend" and "partner" mean different things to different people, the distinctions between the terms are subjective, and which term is used in a relationship will ultimately be determined by personal preference.

When used by a girl or woman about another female in a non-sexual, non-romantic context, the two-word form "girl friend" is sometimes used to avoid confusion with the sexual or romantic meaning. "Girlfriend" is usually used in terms of very close friends and usually has no sexual connotation in that sense of its usage, unless it is in the case of lesbian, bisexual and pansexual women. The term also has currency in LGBT communities and can refer to people of any gender or sexuality.

Though nuanced, there is a significant difference between "girlfriend" and "boyfriend", and "girl friend" and "boy friend"Fact: date=February 2009. In a strictly grammatical sense, a "girlfriend" or "boyfriend" is an individual of significance with whom one shares a relationship. A "girl friend" or "boy friend", however, is simply a friend identified on the basis of gender. The transition between the two is a significant aspect of adolescent development. Some American adolescents have taken to referring to members of the opposite sex who are not in a romantic relationship with said adolescent as a "friendgirl" or "friendboy" to help distinguish more easilyFact: date=January 2009. Others use the Spanish words "amiga" and "amigo" for the same purpose, though they are literally translated to mean female friend and male friend.

This term when used between men and women does not necessarily imply a sexual relationship, but is often used to refer to a woman who is dating a man she is not engaged to, without implying that she is having sex with him. With the changes in sexual mores among some people, the term dating when used to indicate that an adult man and woman have gone out together on a date, can imply romantic activity whereas simply using "friend" would likely avoid inferring such intimacy. It is essentially equivalent to a prior term used, "sweetheart" which is also a term of endearment.