Mao had been very busy lately, and it's caused him to spend less and less time with Ritsu. Which got Ritsu mad and he yelled at Mao. Mao didn't understand why Ritsu was so upset, and got fed up with RItsu yelling at him

Ritsu! I don't have to spend all my damn time with you! You're so damm clingy and annoying! Leave me the fuck alone!