Adapted from a recent online discussion.
Question: Sometimes when my girlfriend comes home and complains or rants about a person or situation (like a coworker or person on the subway), I defend the other person, or, as she says, "side with" the other person. If I think she's overreacting or in the wrong, then, yes, I say so, pretty gently I think.
This reeeeally [ticks] her off. She says she's just venting and that, as her boyfriend, I should just listen to and support her unless she's specifically asking for feedback (which she never is in these situations). I think she should listen to what I'm saying, so she'll see the other side next time and maybe it won't anger her so much.
Am I being a bad boyfriend? Should I just nod sympathetically and swallow my objections? Is that how 60th anniversaries happen?
Answer: Yes, the ones their kids dread having to celebrate but celebrate anyway because it's easier to show up for a few hours than it is to risk the silent treatment/crapstorm/guiltstorm by pointing out that all previous celebrations have devolved into sniping and tears. I think you probably already know this.
I agree with you that people are generally happier when they don't react to every little thing and instead grasp that not every obstacle is a personal attack by the Fates. However, this is not something you can reason, debate, cajole, or pressure someone into believing. You've got to feel it to believe it.
By trying to be her personal missionary of The Other Way, you're crossing the line into meddling. You're her boyfriend, not her emotional tutor. Assuming that role throws your relationship balance way off.
You can only address the part of the problem that's yours: your frustration with what you see as her needlessly combative relationship with the world. Instead of hunting down the magic combination of words that will teach her to chill, it's time to think about whether she's really the right girl for you.
The first step is to banish all "shoulds." She thinks you "should" just let her "vent," and you think she "should" make an effort not to get teed off by every little thing. Strike them and replace them with "won't."
Can she accept that ranting about nuisances isn't going to elicit the reaction from you that she wants? Can you accept that she's not going to heed your suggestion to take things less personally? Instead of defending your own positions, see if you can accept the other's, even (especially?) if you disagree.