He is being very clever actually. Dude very well knows she loves him, she's as good as told him so already but even if he didn't heed her words he is very adept at reading her mind and he must have read it at some time.
That play comes straight out of the "Bad Boys Players Handbook." He has basically told her to go, he is no good for her, if she stays he may hurt her yada yada yada then he makes it her decision to go or stay. If she stays he's got a perfect excuse for every shitty thing he does thereafter. All he has to say after mistreating her/ breaking her heart is "I already told you I'm a bad boy and am likely to break your heart and you accepted me the way I am so you've got to excuse my stupidity. You can't leave me when I've already told you this is likely to happen."
