The fact that Harima avoids Eri isn't something new to her - so she most likely won't be discouraged by it.
For now, the option Eri should take is might not necessarily be fighting and making some love-frontal attack, but just checking what kind of feeling Harima has for her. (just wanted to remind that the topic is about what Eri should do in our opinion).
well i think that the "rejection" caused more damage to harima than eri, It hurt his pride to have his rejection rejected. But i think that its safe for now to say that at the moment Eri is just trying to understand her own feelings. And depending on those she will choose what to do