I am sorry, logically deleting his account is a bad sign.
I mean if he's faithful to his girlfriend, he wouldn't delete his account. And exactly, they haven't been for that long for him to ACTUALLY delete his account for HER!
If he's an honest person, isn't hidding anything, then he wouldn't delete his account. If the account was bothering SO MUCH (because of his past) he would have deleted before even meeting the girl.
But there is certainly something wrong, and she has to be concerned. At last most men aren't to be trusted at all!