[potchip]

Spoiler for If Kobato gets to choose:

Kodaka would not accept Sena if her obsession with Kobato continues - he made specific points to protect/look over Kobato whenever Sena's around. On the other hand Kobato seems to have a decent rapport with Yozora, maybe more because enemy of enemey is a friend because she's seen as someone who can subdue Sena.

Yozora's theme is the tragic main - she represents the past and what might have been but can never be now after 10 years. Her personality being pessimestic - from her discussion about not able to join clubs in the middle of the semester etc is similar to Kodaka. That she spotted Kodaka on his first day of transfer, but never made a move until a month later (some even speculate the air friend could be a set-up to begin with) suggest she's still hurt and only after affirmation that Kodaka still cherish the old history did she really start to make her moves.

Sena is naturally the opposite of Yozora whereas she doesn't care about the past but only the now. Her presence is a catalyst for Yozora to take action and alter her behaviour - for just reacting when Sena naturally calling the shots with Kodaka will put her on the backfoot. That she casually telling the club her past is a sign of forced change - she'd be too embrassed in the past. Though the part about true friend worth more than other friends, that's really just her idealistic view of friendship carried from childhood days, not having had much experience in the matter since.

In terms of Kodaka's feelings he does admire Sena for her efforts, and with Yozora it's really only the past - nothing of her now is really likable. Yet to to be seen how much of past feelings may re-surface though.