When women use the term to talk about other women and their relationship to them as being 'girlfriends' or one of them being her girlfriend, it is usually used in terms of very close friends. It usually has no sexual connotation in that sense of its usage, but it can, in the case of lesbians.

When a man uses the term about a woman, referring to her as his 'girlfriend', or a woman uses it to refer to a status of herself as some man's girlfriend or some other woman and a man as that woman being his girlfriend, it is almost always used to refer to a woman that is involved in a romantic relationship with, or more commonly, a sexual relationship with that (or a) particular man.

The term boyfriend is used exclusively in the complementary sense to the latter explanation, as a man who has a sexual relationship with a woman.

Until the last decades of the twentieth century, this term when used between men and women generally did not necessarily imply a sexual relationship, but was used to refer to a woman who was dating a man she was not engaged to, without implying that she was having sex with him. It is still used in this sense when talking about young teenagers (or even pre-teens). With the changes in sexual mores in effect now, the term dating when used to indicate that an adult man and woman have gone out together on a date, now strongly implies sexual activity between them.

It is essentially equivalent to a prior term used, sweetheart.