Madame, that is by far the ugliest nose I have ever seen, and I compliment you on it—it suits you!
—Peter Sellers, "The Pink Panther"
It's true: Some comments are better left unsaid.
But as a sophisticated man of the 21st century, you already know this. You know you're not supposed to comment on your girlfriend's weight, or tell her that her friends are hot. And you know she probably feels the same way you do about the phrase, "Can we still be friends?"
Additionally, you've found that honesty, while valued in most situations, can sometimes offend. What you say to diffuse tension in an argument often stokes the fire. We understand that the female psyche can be complicated, and we're here to demystify what may seem like strategically placed trapdoors.
"When she asks "Does this dress make look fat?" The incorrect answer (hands down) is "no fatter than the other dresses you own". - One of those things NOT to say! "