Like Crystal said, using a label to qualify the nature of a relationship can help ensure that an accurate perception is conveyed in conversation. What I'm not in favor of are labels being used as a stamp of ownership. "He's my man!" "She's my woman!" How about he/she is my partner? Or "someone special" like Peggy's friend characterized it.

Saying I love you to a special someone, I think, is just as important to most as proving it through actions. Verbally declaring love for someone doesn't have to mean till death do us part to be meaningful.