The truth is, most women don't go through life with the same, single best friend. We're human and thus we evolve, we adapt, we change—and so, too, do our needs. You probably refer to five different people as "my best friend" on a regular basis, and that's ok! No one's counting, and no one's going to say you can have just one. That's like, so Kindergarten, please.

We go through so many transformative stages during the course of our lives, it's only natural our best friends reflect that personal growth over time. What you need out of a best friend when you're 15 is very different from what you need when you're 25, because you're different.

But when you reach post-college life, the speed at which you're changing starts to slow down. There's more clarity about what you want from life, including your friends, which often means it's time to make new ones. Making new friends as an adult, however, is no small feat; you're up against college besties and high school besties and—your biggest competition of them all—childhood besties. On the other hand, the new best friends you make as an adult probably have the greatest chance of lasting you a lifetime for the very same reason you found them: because you have a better sense of who you are, and therefore who you need. You are, after all, the company you keep.

Still, there are certain milestones in a young adult life that together form a kind of right of passage for these types of besties. Whether you can relate to just a few or all, these milestones signify a bond that's built to last.

1. Your first friend date

There is nothing more uncomfortable than that first friend date. You either got set by a mutual friend –maybe you just moved to a new city or you were looking for a roommate—or you managed to make a plan yourselves after realizing there was BFF potential. You probably grabbed coffee like it was a job interview because you were too nervous to have an entire meal together. It will always be the most awkward moment in your friendship, and you will forever laugh about how you caught yourself putting on your "going out" makeup just before.

2. Your first time partying together

A successful night out means a lot in a friendship. Besides knowing you both have a three-drink limit on dirty martinis, it means your friendship isn't restricted to Saturday morning brunch (you know you have those friends). You can now be each other's wing woman and feel totally comfortable stuffing your faces with pizza at the end of the night. No shame, and so much fun; an essential element to the bestie equation.

3. Your first breakup

Going through a horrible, gut-wrenching breakup can also have its upsides. It's a defining moment in a friendship that can distinguish the good from the great. You were comfortable enough to ugly cry and she was comfortable enough to watch you ugly cry while making sure there was always a fresh tissue within a 1-foot radius. It's what best friends are for.

4. The first time you lend your favorite something

Whether it's a designer bag, your favorite black pumps, or that piece of Chanel costume jewelry you found at a flea market, nothing says "I trust you" (and also "I see you all the time") like lending your bestie your favorite something, especially that first time.

5. Your first time traveling together

Although traveling with a friend can be a risky move, a positive experience can also catapult your friendship to great heights. So what if you wanted to spend more time in the museum while your bestie hit the stores? Even if your travelling habits didn't perfectly align, you learned so much more about each other and had a blast.

6. Your first fight

Fighting is never a good thing in any relationship, but looking back you'll probably agree that first fight was necessary, if only to learn how to recover from it. Knowing you could have a disagreement and move past the situation, together, gave you all the more faith that your friendship was a special one, in which openness and honesty were always a must.

7. Your first time meeting the family

Friends can be like an extension of your family, so it only make sense you would eventually introduce them to the real thing. There are few moments in a friendship in which a bestie will learn so much about you so quickly, which can be both good and bad. But understanding where you come from was also insight into who you are, which only brought you closer.

8. Your first birthday together

Let's face it, celebrating birthdays as an adult just gets less fun with time. Planning a party for yourself feels more stressful than exciting and that sexy birthday outfit is just embarrassing at this point. But your bestie decides she doesn't care if you don't like birthdays because she really likes birthdays, and she's going to do whatever it takes to make sure you feel like the Birthday Princess all day long. Don't EVER let her go.

9. Your first time hosting together

Remember when you decided to throw that Chrismukkah party together? People are still talking about it because that's how great you two work together. You handled the supermarket runs while she decorated the apartment, and you wore equally embarrassing holiday sweaters. It's what made you know you were more than just best friends; you were the ultimate dynamic duo.

10. The first big personal struggle

Maybe you got fired from your first job, or perhaps a loved one was ill. She didn't just send a text to see how you were doing, she sent flowers to your office or brought you your favorite chicken soup for dinner –anything just to let you know she was there unconditionally. Knowing that your bestie has your back in your hardest moments is the very definition of a true friend.

11. The first big positive change

She sent your first big published piece to everyone on Facebook, you came to her grad school graduation. She got engaged and called you first (OK, maybe after her mom), you went out for drinks the night you found out about your big promotion. Your moments of glory are better when they're shared, because after all, you wouldn't have been able to do it without each other's support. And sure, maybe you worry a little bit that you'll see her less now that she's planning a wedding and your on-call at your job 24/7, but the thing is, you'll always have each other. With growth comes changes, but if you've come this far together, you're in this thing for life. You may not always throw parties together or spend every single birthday in the same room, but you'll always be there for each other in spirit, because you've had TIMES. Man, have you had times.

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