Yay, more Yodokawa!
I also thought this was charming, and a more realistic depiction of how a relationship can look.
I'm amused at these hyperbolic takes about how they should break up, or how Mei is a horrible person, because she's absent minded and a little messy.
Some people just are that way. It'd mean pretty much anybody with ADHD is a horrible person by default.
You can be kind of a mess, and still have plenty of good qualities.
Also remember that they're just roommates (lol). That makes her a bad roommate, not a bad girlfriend. Pretty significant distinction in my eyes.
Also, Yuiko should really communicate her actual feelings better. Come on, bud.