1. That first awkward, nervous pause right before your first kiss. Your first kiss says, "I like hanging out with you, but I also want to make out with you all the time. Let's take this to the next level."
2. The first time you bone. Well, hopefully your first time was a great moment. And if not, you're a very selfless person for sticking with them.
3. The first time you stay the night instead of abruptly peacing-out like Cinderella the second it hits 2 a.m. Especially if you usually run off into the night immediately after coitus. Well, maybe hobble into the night while trying to put on your pants is a more apt description. My point is, your first sleepover is a big deal.
4. When you did nothing in bed together and it was amazing. The first time you do this, it's cute and romantic. The 90th time you do this, you're codependent agoraphobics. But when you can literally spend all day sharing a tiny square together and doing nothing else, you've got something good going.
5. When picking your partner up at the airport felt like the best moment in the world. Spending time apart (however long) is rough, but getting to see each other again makes it all worth it. All right, maybe it would've been better to not be apart in the first place.
6. Buying a second toothbrush to keep at their house. You're basically saying, "I'm coming over whenever I want so you can never cheat on me." But also, you know, that you love spending time together.