Responses
I dont think Maki did that to make Rin jealous but he saw the girl is his enemy. If he gave Rin the letter, perhaps Rin would accept her as his GF. And Maki didnt want it happens so thats why he didnt give the letter.
Ithink Rin is the manipulative one of them... like his personality in general is more capricious and demanding
Maki really genius, he manipulate rin chan and finally have him all for once and forever ever. I realize first coz the letter accident. Maki know rin chan see them but he keep lying just to make rin chan jealous and lonelly so he fell depent to maki. Super sly.