Yuu is soooo into Mari, really just her touching someone else made you get so jealous? lol but she does seem to know her limits and tries to keep cool, even if she blows up at times, it stays at an ok place.
I cant blame Mari for thinking she was about to throw that cake mix.
Do gotta give it to Yuu more then being an asshole she just seems bad at interacting with others and when Mari is not just giving only her her full on attention, even still she just ate up her grievances cuz she knew they were petty to give Mari a happy holiday, now that deserves the highest honors.