Best friends are their own special kind of breed.
They're life partners, soulmates and counterpoints in ways that are totally different from your SO, and they fill voids a romantic partner doesn't have access to.
Best friends never need to "catch up" with you. They're there when shit goes down. They're the only people who get to give it to you straight, call you out on your bullshit and be mean to your face. They're your person.
So, what do you do when yours disappears when she's found a new guy?
Try to cut her some slack.
This is the hardest part about having a best friend shack up with someone. You're used to being partners in crime and sharing the best moments of your life together.
Suddenly, it can feel very isolating to know she's going through something amazing, like falling in love, without you.
Though your feelings of hurt and envy are totally valid, try to remember, this time, it just isn't about you. That's a really hard pill to swallow, and the sooner you can start trying to resolve this for yourself, the better.
She's your best friend, and she's found someone who makes her happy. Remember, you really DO want that for her, so make this your mantra.
Pick your battles.
Are you mad she didn't text you back in 30 minutes, or are you mad because she went to that insane concert with her boyfriend, even though you've been planning to go together all year?
If she's dropping the ball on promises, flaking out on plans or ignoring your personal successes, it's definitely OK to call her out on it.
There is a difference between being less available and being a shitty friend. Make sure you know the difference before you pick a fight.
Be honest, and don't use guilt for leverage.
If you've been patient with the honeymoon phase, and you're waiting for her head to come back down from the clouds, be honest with her.
Let her know you've been missing her, and while you're so, so happy for her, you've felt disconnected.
You might be tempted to point out that this is her fault (because you've just been waiting by the phone to hear from her), but that'll likely stir up resentment on her end.
Remember, you're HER best friend, too, and she'll be looking for you to be happy for her.
Also, never underestimate the weirdness of falling in love. It makes us crazy, self-absorbed, cartoon people who forget societal basics. If you make it about her being a bad friend, she'll likely feel confused because, in her world, only positive things are happening. She might not connect the dots on why you're having a tough time.
Make a real effort to get to know her boyfriend.
Wouldn't it be awesome if you guys could have a "Friends" scenario and live in a giant, badass apartment together with Phoebe?
Your reflex might be to push back on your bestie's boyfriend, thinking if you distance yourself, it will make it harder for them to grow closer. But in reality, if it's inevitable that he's going to be around, you need to accept him in your life.
Tell her to invite him over for movie night, or meet them at a bar for drinks before their dinner date. The quicker you can all make it normal to hang out as a trio, the quicker you get to spend time with your BFF again and learn to love her person as well.
Hey, maybe he has some awesome friends, and then, you can REALLY Ross, Rachel, Monica and Chandler this party.
If they break up, do not tell her you told her so.
This is a passive-aggressive, shitty move and you are better than this.
She is your best friend, she was really happy and, now, her heart is broken. How lucky for her she has a friend like you who is there to catch her, and how lucky for you to have someone who counts on you when they can't count on anyone else.
Stock up on her favorite snack, do that hilarious thing you guys love to do when you're feeling down and tell her you love her.
Never, ever forget you love her.