To all addressing the fate of Chito and Yuuri, please read the epilogue for more information on this topic. I don't want to spoil this for anyone who hasn't read the manga in it's entirety so read on with caution.
The final page of the manga uses the past tense form of a word when referring to Yuu and Chi. I'm afraid for all of you wondering that this likely points to what we don't want to be true. Tsukumizu went through a long period of depression after the ending of the series and I can certainly relate. It would be like seeing your children die to me. While it is sad, I just want this page to clarify any questions about that you might have.