When it comes to dating, we're notoriously reluctant to label anything.
We call ourselves a "thing," not boyfriend and girlfriend (or boyfriend and boyfriend, or girlfriend and girlfriend). We say we're "talking," not dating.
We don't know if one, three or six dates signal the beginning of a relationship -- if it even signals a relationship at all -- and we never know if we're exclusive or if we should actually continue seeing other people.
Most of all, we perpetuate this constant state of questioning ourselves and not knowing where we stand because we're too afraid to confront anyone about our feelings.
And in a world in which we never know when things start, it makes sense that we never really know when they end, either -- except, well, if our ex starts dating someone else.
Now that's how you know a relationship is really, truly over.
The definition of "breakup" might have been unclear, but now it's not
Whenever you ask newly single friends when they and their exes broke up, it's normal to hear them chuckle and say "officially or unofficially?"
Even though you might "officially" end a relationship, you probably don't cut your ex off right away.
You probably still follow him or her on Facebook, Twitter, Instagram and Snapchat, so you still feel like you're a big part of his or her life.
And because of this, you can easily text, message, tweet, like his or her Instagram picture or include him or her in a mass Snapchat to your friends.
Before you know it, the supposed "official end" of a relationship has no meaning.
Eventually, you start talking to your ex more frequently. You might start drunk texting each other and flirting, which might lead to meeting up late at night and having the infamous, you-swore-you'd-never-do-it breakup sex.
For some couples, this could continue for months and months after the official breakup -- until someone else comes into the picture.
That's when your ex's focus shifts away from you and to another person.
That's when the definition of "breakup" is no longer unclear. If you weren't broken up before, you sure as hell are now.
You now have newfound boundaries you didn't have before
During your post-breakup period, it was easy to push your limits with your ex, whether it was with those drunken hookups, calling him or her late at night "just to talk," laughing together at parties or joking about the silly or embarrassing things that happened in your relationship.
When your ex starts seeing someone else, however, you know it's time to back off.
It's not only unfair to you and your ex, but it's unfair to that new person to continue keeping, um, in touch like you were before. You don't want to make anyone feel uncomfortable.
You also don't want the new person getting suspicious of you, so you just act like another person your ex knows (even though this won't work because the new person has probably stalked you to death and knows everything about you anyway -- but that's another story).
You wave from afar, minimize giggling and refrain from having casual texting conversations.
You maintain levels of platonic friendship that you guys had never done before.
These newfound boundaries prove that not only is the relationship really over, but the post-breakup attention you were used to is really over, too.
Every single aspect of the relationship is coming to an end.
The fantasy of ever getting back together is officially over
Deep down inside, you might have had this weird fantasy that you and your ex would get back together one day.
You might have starred in your own epic romance novel inside of your head, subconsciously convincing yourself that maybe, just maybe, those drunken hook-ups and late-night conversations meant the two of you were holding out for each other in the name of a grand love story.
All of that was crushed when it became clear your ex wasn't holding out for you at all.
Or maybe you didn't even realize you were holding on to the fantasy until the moment your ex actually got with someone new.
Maybe you moved on, but an unexpected wave of nausea still washed over you when you saw your ex tagged in a photo with that new person on Facebook, which made you feel betrayed.
Whether you were aware of the fantasy or not, there's no hope of it becoming a reality.
Your ex is with someone else now. The fantasy must remain a fantasy.
You once thought there could never be anyone else, but now there is
At one point in your relationship, you and your ex were convinced there was nobody else either of you wanted to be with.
You guys came as a package. Your ex was your everything, your partner in crime, your number one person.
A world in which you and your ex weren't the yin to each other's yang made no sense to you.
But now, your ex has a new everything. A new partner in crime. A new number one person.
You know how deeply connected you once were with your ex, so knowing your ex is feeling that deep of a connection with someone else confirms the fact that you are no longer relevant.
Despite what you thought previously, your connection really could be replaced. And that's what hurts the most.