No, it's not sad, don't worry... it's happy in a way but it's very open-ended.
yay happiness thingies! How is it open-ended?
You don't know who Yukari ends up with and basically she's gonna become Ryo's manager again... and life goes on (or something XD)
Oh....I see. Seeing scenes with Ayaori and Yukari are so cute. He's dense and she's clueless. 
I know I know !
!I soooooo hope there will be an anime for this!