
You must be fun at parties. T.T

It depends. There are many couples who hook up in high school and stay together for life.
That happened with my father's parents.
My mother's was a bit more complicated. They met after the War and my grandma had my mom a tiny baby. Both of them were 21 and grandparents met at a bar one night, grandpa wanted a family, they married within a week and he adopted my mom.
They were together until Grandma died 2 years back. Over 60 years of marriage.
I think what breaks up most couples is failure of expectations and lack of communication. As long as you talk and discuss about things and fight for the relationship then it can last.

True. But that is mainly due to people not putting in the work to keep the relationship going. Things start to go wrong and instead of communicating and trying to work at it they decide to end it.
Anyone who has ever been in a long-term relationship has usually always reached a stay and work for it or leave situation. It's harder to stay but usually worth it.
My elder brother has had this happen numerous times in his marriage but they are still going strong nearly 22 years later. They truly love each other but they both have their issues and sometimes need therapy to work through it as a couple and every time they choose to put in the work and fight to keep their marriage going.

Yeah. Most of my family is either single, divorced a few times, or in a long-term relationship.
My mom's been married 3 times. She was legally separated to my dad when he became ill and we took him in and he died when I was 12. She's been with my step-dad since 1996. So that's 20 years...
My mom's sister (high school sweetheart) and a brother (college sweetie) have both been married for over 40 years to the same person. Her other brother has been divorced twice. But each marriage was over 10 or 15 years old when it fell apart. First one due to alcoholism (both of them) second one...well, it got ugly (her).
So I have good and bad examples. You just got to know if the relationship and person is worth fighting for. Sometimes it is and sometimes you are better off leaving. My mom and uncle were.
I also think a lot of times people confuse 'first love' and 'crushes'. I've had crushes and dated but I've never had a first love and I'm 32. So I think it all depends on the person and the relationship.
Every time a character says "first love" I start to think that the relatioship won't last, since it's called "first" because there's gonna be others as life goes on.