1. "My ex did the exact same thing!"
Whether it's a positive correlation (they both always hold the door open) or a negative one (neither one showers often enough), your boyfriend never wants to hear that he's anything like your ex. Ever.
You don't want him to feel like you're always comparing the two of them, do you? Think about it: Do you really want him to imagine that he does other things just like your ex? Doubtful. Plus, he might think you're still hung up on your former flame.
Either way, a comment like this won't do much for his self-esteem. So the next time you experience boyfriend déjà vu, keep it to yourself.