1. You can’t be selfish… entirely
Your 20s are a time when you can hop around and basically do whatever the hell you want. Are you over the city you currently live in? Then move! Do you just want to drop everything and travel? Have a Brokedown Palace moment with your best friend (besides the whole being framed for heroin possession and wasting away at some jail in Thailand?) You can! Being in a serious long-term relationship, however, limits your options. Instead of indulging in your every whim, you now have to account for someone else. Say you wanted to move to New York but your partner hated big cities. Or the person you’re with landed a great job but it’s in bumblefuck nowhere. You have to go with, right? The hope is that the love you get from your BF/GF is worth any missed opportunity and oftentimes it is. Still, you have to be conscious of the potential for rising resentment.
2. No more sleeping around
90% of my best girlfriends are in relationships and the number one thing I’ve heard from those who’ve been with their boyfriend for A LONG, LONG TIME is, “Wait but I want to sleep with other dudes. I love my boyfriend, I’m obsessed with his penis, but I just would like to experience another one.” Ha, and you thought men were the only ones who struggled with monogamy. Nope. Girls have trouble committing to one private part too. It’s not because they don’t love their partner. They just want something new and exciting. They want a guy who will make them feel like the sexiest woman on Earth. (Apparently, after five years of being together, you’re not ripping each other’s clothes off anymore. Who knew?) It makes sense also considering that women enter their sexual prime later than men do. I don’t know. Monogamy seems hard. I’ve never really been tested with it but I remember when I was 17, I got mad at my BF for, I don’t know, blinking in a way that indicated that he might be cheating on me? So to get revenge, I invited over the only other gay person I knew in my small hometown and tried to seduce him. It didn’t work though. The guy got too wasted watching Kate Bush videos and by the time I was going to make my move in bed, he vomited all over the place. Sigh. ANYHOO, where was I? Oh right. Yeah, monogamy is a bitch.
3. People change
When you’re in your 20s, you change. A lot. I know this sounds ridiculous, but like I’m 26 and whenever I meet someone who’s 22 or 23 — even if I love them — I’m just like, “Go back into the oven because you aren’t done yet.” Three years do make a major difference in your 20s because every year is like a giant epiphany. When I was 23, I was unemployed and eating pills out of a Pez dispenser. My life today doesn’t resemble that in the slightest. Who I would’ve fallen in love with at 23 is not the same person as today. People outgrow each other. The person who made sense to you in college might not anymore. It’s hard because there’s nothing to blame but time and maturity. They ruined your relationship. Basically, it’s just difficult to have any kind of constant in your youth because you’re constantly shifting your priorities and mind. How can you love someone the same way for years when you can’t even love a TV show or a dress for that long? 
