Well,I made a walkthrough if you can't get the Happy or the best ending,but exploring it yourself is much more fun ^^ but if you really don't get it then here is the walkthrough :) If you don't get the best ending please tell me then I will take a look and correct it
Oh and have fun playing it <3
B. Look down and answer
B. "I like you best"
A. "I'm so happy..."
A. "I don't like jokes like that!"
B. "You're my fiance,right?"
A. Kiss him
A. Push him away
B. "That's nice of you to say."
A. Try to explain
B. "I'm glad you're okay."
A. Silently give control to Saeki
A. Call Muro
B. "It should have a happy ending."
A. Say "There are people around!"
A. "I can't"
B. "I was going to turn him down."