I'm not sure myself. It probably depends on which romances you're talking about The Mills and Boon style ones I find quite unbelievable though. Especially the insane, tumultuous romance that takes place over all of 3 days :)
The ones I read are pure escapism, not just for the sake of the romance, but the rest of the story too, like the girl ends up with the job of her dreams and the perfect neighbour who ends up her best friend and the lottery win and and and.. If I wanted to read about real life I'd pick up a newspaper!