Never tell your girlfriend she could never be as hot as the woman in the magazine (or anything to this effect). Whether you meant it as a joke or not; trust me she won’t find it funny. You say Wow she’s freaking hot! What we actually hear is, God, you cow, why can’t you look like that!
Women (even those of us who are confident with ourselves) have our body image thrown in our face daily. It’s in every magazine we look at, every TV show we watch; Hollywood and Celebrities have done a bang up job of imprinting in our minds what defines beauty and sexiness. We know we are never going to be that girl in your monthly subscription to (your magazine here) nor are we ever going to be a Victoria’s Secret Model, (of course secretly most of us would like to be no matter what our current level of hotness is) but we certainly don’t need you reminding us that we don’t fall into this category.
Never tell your girlfriend to relax. Obviously she is worked up and irate about something and no matter how trivial it may seem to you, telling her to relax is about as smart as walking up to a stray pit bull and smacking it. You say, Relax! What we hear is, You’re being an irrational psycho! Women do not like to be told how they should feel about any situation (realistically I don’t think anyone does). We want our feelings to be validated or in the very least, acknowledged. Although you may never understand our feelings, we still want you to respect them.
Never tell your girlfriend that you’re never getting married. Although most of us (not always) are more ready and willing to get married sooner than you are it doesn’t mean we are trying to drag you down the isle kicking and screaming. But we also don’t want to hear your pre-pubescent plan that you intend to stay single forever.
You say, I’m never getting married. What we actually hear is, You’re not good enough for me. Then, say a few years down the road (ready for this?), the two of you are still together and you incidentally propose (now you’ve done it); you really don’t want her to get the impression (and continue to wonder throughout the years) that the only reason you are asking her to marry you is because you’ve succumbed to the dreadful realization that she is as good as it gets and you figure you can’t do any better. If you already plan on proposing at some point, or you’re really not sure yet, maybe you really don’t want to get married; either way it’s best to shut your pie hole and keep it to yourself.