Ko is a very understated character in this series, and given the setting, very undeveloped and perhaps even unappreciated. What a lot of people don’t realize is that even in his absence, he is the major personal crutch of Ohana. Ohana thinks about him a lot, about his belief and opinions, and perhaps even more telling is when she wonders how Ko would react or assist in her situations. When Ko called her up to ask about her and where she is, it instead becomes an avenue for Ohana to again ask Ko for advice. For someone who once strove so much to be independent and capable, she relies on him a lot more than she realizes. What was supposed to be a chance for him to reconnect with her became a debriefing session, ending up with Ohana finding courage to continue on and thanking her best friend from the bottom of his heart. By helping her he sacrifices his opportunity to be with her and speak his mind. By giving her advice he somehow pushes her farther away. By being a great friend, his chance at romance goes down the crapper. Poor bastard.
Despite his obvious depression at his situation, he still did everything with a earnest and open heart befitting a true friend. It’s again ironic that by being a true friend he’s perhaps messing up his chances at being more than that with Ohana. But that’s who he is, he can’t leave Ohana alone and push his own terms at her, because he cares. He cares enough to know that she’s in trouble and that he should help her first, and make his own concerns second. He cares for her enough to swallow his pride, do what he can for her, even if it leaves him cold and dry. He cares (and perhaps loves?) her enough to know not to be selfish, to accept her impositions on him, even if in the end he’s sacrificing for it.
He is depressed, yes, but perhaps sacrifice is all part and parcel of his endeavor. It is the price he has to pay for his chance. He knows enough that being selfish on his part would take him nowhere. I’d say Ohana has learned to appreciate him even more than she already does. Absence had somehow made the heart grow fonder given the number of times she thinks of him. If anything, she’s probably starting to see him in a better light, a light that perhaps may shine on her and convince her that he’s serious, and maybe even cause a change within her owns self.
In any case...