1. You're going to spend a lot of time with them.
Her friends are her everything, which means she's constantly got something going on with at least one of them. But she's not just trying to drag you along—she loves you too and wants you to be a part of all those things.
2. Her best friend comes first.
Her relationship with her bestie is just as important as her relationship with her family, if not more so. This is her first soulmate, and she'll drop everything—even you—if her bestie needs her.
3. Don't be threatened by it.
It's not a competition. She'll love you with all her heart and soul too; we just mean the F when we say BFF.
4. She probably has more than one best friend and you better know the difference.
Yes, you can have more than one person you consider a best friend. Don't question this, and definitely don't confuse them between each other.
5. This goes for her different groups of friends too.
There are her childhood friends, her college friends, her work friends, her book club friends. You don't have to be besties with all of them, but you should feel comfortable with at least a few friends in each crew. Knowing all their life stories wouldn't be a bad idea though.
6. She will judge you by how you treat her best friend.
Do you treat her like gold? Treat her best friend like platinum crusted with diamonds. All she wants is for the two of you to not only get along, but become friends too; after all, if things work out, you'll be part of each other's lives forever as her two most important people.
7. You'll get to have a lot of guys' nights, because she'll be out having girls' nights pretty often.
If you like to get alone time, this is the girl for you.
8. Her friends will join in on your plans with her.
Oh, were you going to get dinner with her after she grabbed an after-work drink with her friends? Better change that reservation from two people to five.
9. You're going to go to a lot of weddings where she's a bridesmaid and you have to entertain yourself.
This means chatting with her friends, not hiding in the corner with your phone.
10. You're going to go to a lot of birthday parties.
No, this is work Sara's birthday, not high school Sara. Hers is next week.
11. Basically, just be prepared for a lot of group activities.
12. You should probably make friends with her friends' boyfriends.
Otherwise it's going to be a ton of small talk while they giggle in the corner.
13. She'll have many, many stories.
Stories about her day. Stories about a thing that happened on gchat. Stories about the thing she just remembered happened at the bachelorette party last weekend. Stories about why five of the six people at dinner tonight aren't friends with Kelly anymore, but you can't bring it up because of the one person who still likes her. She knows it's a lot. Please just listen.
14. Make plans with her in advance.
This goes for all women, really, but chances are her schedule fills up very quickly. Help her make sure you're in it regularly.
15. You probably won't get to be alone with her on her actual birthday.
A lot of people love her and want to celebrate with her. Make special plans for the day before or after for just the two of you.
16. Many people are going to weigh in on your life choices.
Whether you should take that new job? A small committee of her friends have already talked about it. Where you're going to dinner tonight? They decided that too, whether you know it or not.
17. If you get married, figuring out your wedding party will be a doozy.
She's going to be really, really stressed out about who to include. Help her talk it out.
18. She's incredibly thoughtful, considerate, and loyal.
Why do you think so many people enjoy spending time with her? She treats all the people she loves really well, including you.
This article originally appeared on Cosmopolitan.com. Minor edits have been made by the Cosmo.ph editors.