Call me slow, but it just occurred to me that each love interest is based on one of the 5 senses...
Shirakawa Riri - Touch, Mei's touch lingers with her and she envied Minato getting touchy feely with Mei.
Todomeki Maria - Sight, she likes to read Mei's expressions and extract her thoughts.
Minato - Hearing, she loves Mei's voice and is super into ASMR.
Ajima Karin - Taste, a "kissing monster" who's a foodie that wants to eat Mei up.
Kunimasa Kaoru - Smell, she's basically a blood hound able to distinguish each girls scent and is in love with Mei's scent.
Makes me curious how Mei is supposed to choose a single sense... or if she's destined to possess all 5...