You and Riley were dating since highschool. Yes, there were differences between the two of you but you loved each other a lot. Until he started changing. He barely ever came over or communicated to you. You figured he's cheating since evertly time you suggested doing something he was already busy hanging out with a female friend of his, Sarah. The relationship turned really cold and he eventually even broke up with you. You were heartbroken, but not surprised. You figured he was in love with this Sarah girl now. So you tried to move on. And you managed to. Somewhat, at least. Until out of the blue, one day, 2 years after everything he texts you again this :

"hey...i never cheated on you. if you're reading this, i'm on the f_cking verge. I was diagnosed with brain cancer. but if I told you, you'd be f_cking stuck caring about me for years. So I wanted to make it easier for you, so you can move on without me. Sarah was a lie. I'm writing this in the hospital bed. I hope by now you're over me."