You can do better. It started one night when we realized that we were both pining over the respective guys that we were seeing (or maybe more accurately, trying to see) and evaluating our own behavior towards them, asking what we could have, should have, would have done differently.
Then we realized that we could have, should have, would have done nothing. If the way these men were treating us was making us unhappy, then why should we be questioning ourselves? And "You can do better" was born.
We realized that if someone's behavior is a source of unhappiness or discontent, then not only would we be unable to change the person to make us happier, but it wouldn't even be worth the effort! So we made a list of everything that made us unhappy, everything that we should not allow ourselves to settle for, and said that if someone we were seeing belonged on the list, then we could do better. Sometimes it's funny, sometimes it's heartbreaking, but it's always true. And once it was written down, it was like a big dose of reality and empowerment rolled into one.
The purpose of "You can do better" is not to set impossible standards or refuse to compromise. "You can do better" is about not compromising respect and fulfillment. It doesn't matter if he's into you or not, but if he can't pull it together for you, then you can do better!
If he doesn't bother to let you know he's going out of town when you had plans to hang out, then you can do better!
If you find yourself telling him that you have a boyfriend when you really don't, then you can (both) do better!
If everyone tells you you're the perfect couple and you feel like you talk about everything but he breaks up with you anyway without any kind of warning and says it's because he's not happy, then you can do better!
If he lies about his feelings for any length of time before breaking up with you and even goes as far as to tell you he loves you before breaking up with you, hugs you while he says "I'm breaking up with you" and gives you a sympathetic smile afterwards, then you can do better!
If sometimes he greets you with a hug, but other times he acts like he barely knows you, then you can do better!
If he begins statements with "all men" and what follows is a generalization about their sexual preferences, then you can do better!
If he proposes marriage because you mention that you inherited 2,000 dollars, then you can do better!
If he cuts you off when you're discussing your thesis topic with the statement "I'm a student of the law," then you can do better!
If he tells you that your shyness makes him "want to do weird stuff to you," then you can do better!
If he rear-ends someone with your car and then makes you switch places so it looks like you were in the driver's seat all along, then you can do better!
If after you've told him you have a crush on him, you ask how he feels about it, and he answers "neutral, but not repulsed," then you can do better!
If he vomits out his car window while driving, but doesn't stop the car or slow down, then you can do better!
If he thinks he has had a successful summer because he got three people to take up smoking, then you can do better!
If he has, or has had a reputation as the "dormitory bicycle," then you can do better!
If the thought of him reproducing makes you cringe, then you can do better!
If your introduction to him involves him breaking a glass (because he's stoned) which lodges shards in your foot, then you can do better!
If he's stoned so often that you can't distinguish when he is from when he isn't, then you can do better!
If rereading one old email from her makes you feel instantly suffocated, then you can do better!
If she feels compelled to say "It's not like I'm needy, but...", then you can do better!
If he inexplicably and noticably avoids eye contact for an entire night after flirting with you, then you can do better!

If he goes to a party with his ex and has a drunken "accident," then you can do better!

If his idea of courtship is trying to get you to drink at work and then leave early to hook up with him, then you can do better!
If he makes that gesture that involves holding up both fingers to his mouth and sticking out his tongue (you know what I'm talking about), especially referring to two girls who are merely greeting each other in a friendly manner, then you can do better!
If even (to be distinguished from only) in your dreams he's a jerk, then you can do better!
If he sends you drunk, emotional text messages and then acts like you're crazy when you later address his concerns, then you can do better!
If he writes a song about wanting to catch Chlamydia, then you can do better!
If after several dates, he texts you saying that he's too "...distracted" by his ex to call you, then you can do better!