Page 17 was definitely a confession. I think there may be rules for manga in certain publications ratings that they can't have blatant incest. Its always only implied or hinted at or joked about unless its porn or seinen.
Take Oreimo for example. SPOILERS:
Everything in that finale pointed to the siblings staying together, Kyousuke rejects every girl in his life for Kirino but then breaks up with her, only for the author to hint that they stayed together behind everyone's back in interviews. And then the author's next work features STEP siblings. And the Oreimo visual novels that feature Kirino ends retcon them to be step siblings as well.
So don't be quick to blame the writers. Sometimes their hands are tied and they have to work with what they got. We just have to believe in their intent. I believe these two confessed their love in page 17 after that fade out.