I don't see Yarino as a love rival for Tsubaki at all. Kiritsu has been inner-monologuing his concern for how Tsubaki sees/communicates with him for awhile now. That doesn't mean he won't recognize talent, especially talent akin to his own, and be gracious enough to commend it, in his own way. It's clear to me that Yarino does not like people who belittle or bully others, and probably sees Kiritsu and Tsubaki as both of those. Beyond that, she's got a bit of a potty mouth, and I don't believe Kiritsu would easily go for that type of girl.
Regardless, this should be a wake up call for Tsubaki; she needs to realize that the world, in fact, does not revolve around her: ditching the lustful delusions will be a good start (though the fanservice will suffer).