The media (film, more specifically) sets a precedent that says unless you have x number of friends, had x number of girlfriends, had sex with x number of girls, then you're not cool. This then sets viewers' expectations high and only leads them to inevitable disappointment.
The standards set by the media are unattainable 100 percent of the time; it isn't possible to be laughing with friends or set in a romantic scene with your special other every day, all the time. But in films, all viewers witness are the good, interesting parts of so-and-so's life.
I come to the conclusion then, that while I may feel lonely lacking a girlfriend, I shouldn't feel this way. After all, this sense of loneliness is artificial and has come about only as a result of hours of romantic movies and romantic comedies.
And although I realize these romantic movies are probably detrimental to my self-esteem, I enjoy watching them nonetheless because they portray a fantasy (relationship) I feel I may never attain. It's then fun to put myself in the shoes of the protagonists and to imagine, "what if I had a relationship? What would I do in this exact situation? How would I get out of this rut in a relationship? Would I be capable? How would I deal with losing a girlfriend, fiancée or wife?" Romantic movies provide such escapism for me.