Tamura

Tamura has been your friend since birth. You were always together, and besides Tamura, you had your quirks as a child. Tamura is calm and gentle—in short, he's like a marshmallow inside, and you took advantage of that. He did everything you asked, even if it involved the one he loved most. You thought like this:
"If he's friends with me, then he's only mine..."
Actually, you always lived by this principle. You were only friends with him, while Tamura had other friends, but only boys, because if girls started to be friends with him or even just talk to him, you immediately made it clear to those girls that he was your property.
And then one day I noticed a girl hitting on him. (Your actions?)