The minutes, hours, days are ticking by and you despondently sit and wait ruminating on why it seems like your relationship is going nowhere. "What is going on?! Did I do something wrong? Then, suddenly, the phone rings and you are invited on an impromptu date. Per the norm, you jump without hesitation and immediately get ready. One clear sign that the person you love is using you as a backup girlfriend is the amount of time you wait around to be contacted coupled with being asked out at the last minute. If it feels too long and dates are at the spur of the moment, you could be a backup girlfriend.

A holiday is a special time shared with loved ones, and, most importantly, with the love of your life. If you find yourself alone on every holiday, left with is a barrel of excuses, or a plan is made, but you end up wasting the holiday waiting for someone who never shows up with no excuse, this might indicate that you are unwittingly the "stand-by." When you finally do get together, there is no present given for the recently passed gift-giving holiday.

When a relationship is approaching the "serious" stage, an introduction to the family is in order. If, after dating someone for a significant period of time, you have never met the family, there's a good chance that something is being hidden. Actually, there's a good chance that you are being hidden. If your special someone regularly visits with the family and you are never invited -- ever -- then, you must ask yourself why you are being kept a secret. Possibly, someone else is being paraded around as the girlfriend or you are on "backup" speed dial, until that day when someone perfect is in the picture. "If you're not his routine 'plus one,' it's a definite indication that you're not his girlfriend," suggest Natasha Burton et al. in "The Little Black Book of Red Flags."

Strange isn't a strong enough word to describe watching your special someone leave your side all dressed up with nowhere to go but home -- or that's what you were told. Changes in appearance, habits and hobbies are all clues that the person you spend time with is spending time with someone else. If new clothes are bought that are never worn in your presence, or rock climbing magazines hold tremendous interest yet you have never climbed a rock bigger than the pebbles used for general landscaping, you should ask yourself who is sharing in these adventures with the one you are dating.

When psychologist Galena K. Rhoades and colleagues examined the stability of unmarried romantic relationships in their study published in the "Journal of Family Psychology" in 2010, they found that, "material constraints, such as sharing debt or owning a pet, are associated with staying in a relationship." If it's kept casual without any move to share life's responsibilities, the relationship isn't likely to go the distance. So, if your significant other shudders at the thought of co-signing a lease or getting a pet python together when you both adore them, chances are your relationship is an "aside" being kept around until someone worthy of a commitment comes along, which makes you the backup girlfriend.