When you're single, you develop an innate, sharply-defined sense of when NOT to text someone back -- you might not always follow this guideline (particularly when blood alcohol content is involved), but you're in a constant state of HYPER-awareness about who texted whom last, who's turn it is to text next, how long to wait before texting, what time of the night to text, when to ignore someone for a full month, etc. All the basics.
Once you've been dating someone for awhile, you'll find yourself sending four straight texts to the person in succession without a hint of self-awareness, and all of them are somehow about picking up olive oil at the store.
Should you suddenly find yourself single again, you're gonna come off like an overanxious thirsty creep no matter what, even though in reality you're just, like, being mature enough to not pretend you aren't holding your phone literally at all times, including on the toilet, like everyone is.
When you're single, not only are you fully aware of every party going on, but you also have a mapped-out, detailed route to hit all the necessary parties in a given weekend evening while also optimizing your arrival-hours at each place in a way that maximizes your chances of running into the person you're most interested in sleeping with.
When you're in a relationship, you couldn't care less about which single friends are attending which parties at which times; you can just go to any parties any time, leave any time, or use each other "not feeling well" as an excuse to all the crappy stuff guilt-free.
"Well, I'm single again, guys. So what's new in the world of online dating? Are people still finding mates by adding prospective singles to their Myspace Top 8s?"
SINGLE = OMG she used a winky face. AND an exclamation point. Is that flirting? It's flirting, right? Has to be. YES! This is now ultra-sexual. BUT WAIT -- SHIT! If she were actually flirting, she'd be playing it cool, right? And that definitely means no winky face. MAYBE like, sunglasses-dude face or some food emogee, but a straight-up wink? WAY too on the nose. Dammit. I was so on board with this person too. Guess I have no choice but to not respond for seven days then type "k". Lower case. You break my heart like this, you don't even DESERVE caps.
RELATIONSHIP = Oh cool this text has information in it.
When you're single, you are CONSTANTLY aware of the newest cool things to like, or at least to say you like, as well as extremely aware of the correct retro things to be into, and are ready at all times to make a kick-ass playlist full of cool music that shows off your taste and personality while also exposing your romantic interest to your unique mix of cutting-edge music and semi-obscure but awesome older music that will simultaneously enthrall and impress them.
When you're in a relationship, your cool playlist-making ability stagnates, and all you can make are playlists with the songs you ACTUALLY listen to on them. Which is great, obviously, but HOLY SHIT you do not need a prospective romantic interest being exposed to that too early and blowing the whole thing.