10. You only go on weeknight dates.
Simply put, weekends are reserved for actual girlfriends (or "main chicks" if you're seriously terrified of commitment). There's nothing wrong with a Wednesday night date or meeting for lunch on a Friday, but if that's the only time he can see you, there's a good chance you're dealing with a dude in a relationship.
9. You never get to meet his friends.
A lot of guys are hesitant to introduce their love interests to their friends, as they're concerned one won't mesh well with the other. That said, if he isn't in a relationship, he'll probably let you meet some of his friends so they can see you actually exist. Every guy has that one friend who always claims to be seeing some hot gal but she happens to be gone all of the time, and we don't want to be that guy. On a related note, if he's always going out with his friends but never tells you where they're going, count that as a double red flag, because he might think you're going to track him down.
8. He always has his phone on him.
For one thing, if you were really relationship material in his eyes, he probably wouldn't be glued to his phone all the time. We're not saying you're definitely a side chick just because he's constantly texting or Tweeting or posting status updates, but there's probably something going on if he won't let you look at his phone. Beyond that, you're probably a side chick if you text all the time but never talk on the phone, but you're definitely a side chick if he has you saved under a fake name. We don't personally know any guys who use multiple phones, but that should be considered an automatic "yes" if you're wondering if you're a side chick.
7. He won't hold your hand in public.
Ladies, some of us just aren't into public displays of affection, but there's a difference between not wanting to kiss you in front of friends and treating your hand like the plague on a date. Don't get yourself in a tizzy if he doesn't want to kiss you or put his arm around you with his boys around, but it should cause a little bit of concern if he won't even hold your hand when it's just the two of you out in public. Additionally, if he starts looking over his shoulder or acting weirdly paranoid, it's probably not because he's worried about a sudden ninja attack. He's likely just making sure no one who knows his significant other is within eyesight.