If your girlfriend is hyperventilating, balling her eyes out, sitting in silence, biting her nails, constantly questioning everything, you better not dare ask her to relax.
And if you do, best wishes to you.
Telling your beautiful, anxious mess of a lady to just calm down, will only make matters worse. She will start ruminating about how she is so anxious, how she can't stop, how she may be judged, yada yada yada—it's just a loophole of negativity and constant overthinking. Instead, tuck her into bed with her anxiety blanket that smells like lavender. Bury her in kisses until she can't help but giggle. Uplift her with motivating words.
Anxiety is not logical, don't try to make sense of it.
That's the most influential advice I can give. You may not understand her worries, but no one is asking you to understand. We would all just be banging our heads if we tried to comprehend the rationale behind anxiety.
You know your girlfriend best. What kind of support does she need when nothing else seems to be working in her life? What kind of support would you want to hear if you were troubled by life? Whether your girlfriend suffers from anxiety or has just been having a hard day, week, month, year, she needs your shoulder to cry on.
Everyone has their own opinion on what they need to hear or rather what they are repelled by. Personally, I never feel better when someone says, "It's normal, everyone gets anxious." I have my own individualized fear. It's true that other people have similar feelings, but, at the moment, I'm solely concerned about my distinctive troubles. Yet, some people like to hear that others feel the same way–dealing with personal anxiety is in itself, different for everyone.
But, no fret, there are universal comments that will help you stay calm and, more importantly, will relieve her insecurities.
Here's what to say to your girlfriend with anxiety:
"You aren't stupid and neither are your emotions."
Validate her emotions and the way she is feeling. Her worries may not be logical, they may have no base, they may be small or tremendous, but they are her true, genuine feelings! That is not foolish. You can't take that away from a person. So, acknowledge that you understand that she is feeling some sort of way and that it's alright—emotions aren't silly! Her anxieties may be racking her mind and creating tremendous pain. Don't let her throw them under the carpet. No, stand up to them and delve through the shit.
"I love you no matter what."
Keep it simple. The three-letter-word, "I love you," has powers like no other assurances.
"We're in this together."
Remind her that she isn't alone. It's not her problem. It's both of your problems that you will solve together.
"Let's watch something funny."
Or tell a joke. Or act silly. Or... do anything to make her laugh! Laughing is truly the best medicine. I'm thankful for my "anxiety boyfriend" who always knows the perfect dog or baby or, better yet, dog and baby DM that'll ensure my three-mile-smile.
"Is there anything I can do? And if not, I'll just be here."
If she has a tendency to worry, talking about it may be too overwhelming. Having you scurry around the room trying to do things for her may be too much to handle. Alternatively, be patient and just ask her what she needs. If there is nothing you can do, just being there, listening, and giving her time will be doing everything.
Say something distracting
Distraction is one of the coping methods for anxiety. Help her out by drawing her away from the troubled thoughts by uttering something ridiculous.
"You can't control it."
She can't just miraculously calm down. She can't just let go of the tumultuous sentiments. She can't entirely control her anxiety and that's okay. Remind her that it'll be alright. There are ways to manage unease and she can feel better.
"You are strong"
Refrain from cliche sayings, advice, inspirations, be real. And, reality is, she is strong. As human beings, we are durable, brave, and ready to take on every battle. Don't let her forget her resilience.
"Do you want a hug?"
From time to time, feeling a warm embrace from a loved one is all that one needs to feel secure.
 "Let's just cry it out."
Grab some tissues and let her cry all the angst out. Snot and all. At the end of the crying fest, her body, mind, and soul will feel at least a little bit more at ease.
 "You can talk to me."
Let her know that you are there for her and ready to listen. If you feel like she needs guidance from a professional, kindly motivate her to see a therapist or psychiatrist. There is no shame in therapy, medication, and reaching out for help.
 "I believe in you."
She may not believe in herself, but hearing that you have faith in her, will strengthen her personal confidence.
 "Let's breathe."
I think this is better than saying, "just breathe" because whereas the former statement can seem offputting, abrupt, and mechanical, saying, "let's breathe" focuses on the communal behavior of finding peace within one's own body and breathwork.
 "Let's shake it out and dance."
Start shaking that booty becuase I want to see your happy dance! It works for Dr. Meredith Grey, so it's bound to work for your girl.
 "Name three things you see."
Conspiracy theories are just that, theories. Focus on reality and bring her back to the present moment by asking her to name three things she sees, hears, and feels.
 "I'm here."
I always stand by the little things, remarks, and meanings. Staying simple and to the point can express more than any extravagant action.
Rember to focus on her. Ask if she needs anything or if she just wants you to listen or if she just wants to sit in silence.