I'll also translate a little bit that might help you understand what they had in mind
------------------------------------------------------------------------
「僕」と「俺」
「私」と「あなた」
人それぞれ個性を持っているように、価値観だって無数に存在する。
彼ら彼女らが抱えている『悩み』も、みんな少しずつ違っている。
そして、その『答え』にだって、唯一絶対の正解なんてない。
だから――【 Myself;Yourself 】
-- found on the bottom of
http://www.yetigame.jp/myselfyoursel...ct/product.htm
------------------------------------------------------------------------
「Boku」and「Ore」 <--
(both mean "I", but refers to Sana and Shuusuke since Sana refers to himself as boku while Shuusuke refers to himself as ore)
「Atashi」and「Anata」 <--
(means "Me and You", I think it refers to Nanaka since she refers to herself as atashi and Sana as anata at the start of the game)
Just like how each of us hold different types of personalities, there exists countless set of personal values.
The 『worries』 he and she faces, they are all a little different too.
Thus, there isn't a single absolute correct 『solution』 for them.
Therefore -- 【 Myself;Yourself 】
------------------------------------------------------------------------
So the way I see it, it's also a bit about how we, due to our different established personal values learned from our past, will approach a problem to find a solution. For example, how Shuusuke helps Nanaka vs how Sana helps Nanaka, will determine how Nanaka ends up. It depends on their own personality, how they perceive Nanaka now and in the past, .. etc etc. It's much clearer in the game since there are a lot more inner dialogue to analyze.