Marylene
When Mary and Marlene were thirteen they made a deal that if neither of them were married by forty, they'd get married to each other. A couple months later, Mary decided that forty was too old to get married, and they changed it to thirty-eight. In fourth year, Marlene began to fall for Mary, and convinced they should bring the age down to thirty-five. Mary agreed, and two months later they brought it down to thirty-two.
By fifth year, the agreement was thirty. At this point, Marlene had given up on her unrequited crush, and was attempting to move on, meanwhile, Mary was just starting to catch feelings. Just after Christmas, Mary demanded the age be decreased to twenty-eight. During sixth year, both girls experimented with dating, and although neither of their crushes had diminished completely, they were both starting to move on, and they forgot the pact they had made. On their last day of school, the two girls snuck off together, and as they reminisced on their years together, they remembered the deal. The upcoming war was weighing on all the students, especially those who had decided to fight, and soon the friends found themselves agreeing to reinstate the agreement, but they adjusted the age to twenty-five, as neither of them were sure of their futures anymore.
During the war, as they began to lose more soldiers, the two bonded over their fears, and became even closer. They cried together about how scared they were of nearing their deaths, and one night they decided to change the age limit to twenty-two.
Mary's birthday was first, and when they celebrated, Marlene said to her, "We're halfway there."
On Marlene's twenty-second birthday, Mary made two matching rings, with two 'M's intertwined engraved on them, putting one on her ring finger, and using the other to secure a bouquet of Marlene's favourite flowers, which she placed on Marlene's grave. She read out the vows she'd written for their wedding at thirteen years old, that she'd added to every time they altered their pact.