Ok I can't really hate Izumi after the last Chapter. It's clearly indicated that she had feelings for Nanaki since forever.
It's gotta hurt to see her taken away, first by some a**hole guy, next time by another girl (even if they don't realise their feelings). Sure, she does it the wrong way. For example she showed Nanaki the picture of her cheating (ex)boyfriend in front of all the other girls. This had to be calculated, it just backfired. She's a teenage girl that has to handle her feelings for someone she thought she'd never have a chance with, but suddenly she develops feelings for a girl? Damn, poor Izumi.
(Not gonna lie, tho. If all of the signals are just misleading af and she actually likes Kanade, I'll be surprised)