1. He breaks out in spontaneous sweats even though, um, it's November, and it's winter, and the heat in your apartment is broken.
2. He checks his pocket obsessively to the point of random people asking you if he has some sort of issue. Weirdo!
3. He suddenly has an intense interest in your jewelry (and the jewelry of strangers), like to the point of rifling through your jewelry box when he thinks no one is looking. And then one day your grandmother's ring mysteriously goes missing.
4. He cries for the first time—even at cheesy commercials. And this is the guy who wears his seventh grade basketball jersey to watch the Knicks play on television, would never crack bro code if his life depended on it, and proudly displays his beer pong trophy from 10 years ago. Yes, that guy.
5. He starts clipping coupons—and keeps a binder of them arranged in alphabetical order. All of a sudden Mr. Big Spender becomes Mr. Big Saver overnight. When you ask him what gives, he says he's trying to be "responsible." What the what?
6. He has conversations—with himself, which you can't really make out because you don't want him knowing you're listening, but they're very lengthy in nature and it's all very unsettling.
7. He's overly concerned with your schedule and wants to know your whereabouts every half hour—for the next three months.
8. He won't let you within a 100-foot radius of his phone and when you overstep his bounds he shrieks like a little girl and locks you out of the bedroom.
9. He seems obsessed with your father, who usually annoys him, and wants to know how he takes his coffee, what color ties he wears, and starts brushing up on New York Giants facts even though he'd rather get his back waxed than watch them play.