Have y'all seen how nice Kanade was to Iroha? So far there have been more pure romance moments between pairings Iroha x Kanade and Izumi x Nanaki than other way around.
You know, being kind to someone and being attracted to them are completely different things. You can have a great friend which you help out in times of need, and whom you care for a lot, without either of you feeling the need to get into each other's pants. And you can stumble upon someone in a party and fall in love after five minutes of conversation.
Kanade and Iroha are great friends. Let them stay that way.