You know, as soon as I saw "yandere" and "Would you ever harm your crush" I was tempted to stop reading this then and there. But I kept going.
"Carving (your) name on her arm" is extreme, but if it's truly consensual *and the relationship is healthy*, who am I to judge? So I kept going.
Then I read about the part about taking your crush's life, possibility through a murder suicide. And then I decided to actually stop reading... because why would I trust someone who'd kill me if they couldn't fucking have me?
Well, let's hope OP gets mental help before he commits victory position with his lover.