Both of them are the reason

A boy and a girl meet in school
She was the reason he tried to impress her
He was the reason her knees felt weak whenever he was near
She was the reason he started to send her flowers every morning
He was the reason she couldn't wait to get to school
He was the reason they eventually became a couple
She was the reason they were each other's dates to prom
He was the reason why all of their dates were utterly romantic
She was the reason he got accepted to the same university as her
He was the reason why they decided to look into getting an apartment together
She was the reason they had enough to afford it
He was the reason she got the courage to move out and live with him
They were both the reason they were happy...

He was the reason why she needed to stay late for school work
She was the reason he needed to provide money to keep their place
He was the reason why they slowly stopped going on dates
She was the reason he was stressed with school and work
He was the reason why she couldn't focus in class
She was the reason why he never got good graded in his major
He was the reason why she flunked out of her college class
She was the reason he was let go from his job
He was the reason why they started yelling at each other
She was the reason he sometimes slept on the couch
He was the reason she cried herself to sleep
They were both the reason they had regular fights...

He was the reason she started to drink
She was the reason he stayed out with his friends and partied
He was the reason that she hated the person she'd become
She was the reason he never wanted to be home
He was the reason she wanted to see a therapist
She was the reason why he started taking drugs
He was the reason why she didn't have enough energy to start her day
She was the reason he woke up next to a different woman from the night before
He was the reason she went to the store to buy rope
She was the reason why he remembered that she still loved him
He was the reason that she tied the rope into a noose
She was the reason why he wanted to go back home and apologize
He was the reason she could feel her heartbeat slow down to a halt
She was the reason he opened the door
And she's the reason why he looks down at her gravestone
She is the reason he will never love again
And she is the reason why he will suffer alone tlll his final days...