If your girlfriend suddenly becomes a neurotic spaz questioning your every move (er… more than normal), you can likely thank the various lady mags responsible for feeding her the BS they like to disguise as "relationship advice."
If she believes these seven gems from Cosmo, basically, anything you do equates cheating. He's grooming himself? He's probably hittin' the hot neighbor. He's overly protective of his iPad? Boinking the waitress. Does he seem (God forbid!) happy? He's doing your best friend. But what's especially baffling? No. 5.