I agree with the previous two, Shou is not revenge on anyone, that's just the way he decided to finish Stretch, but it seems that it is customary in this forum crucifying an author for not giving what people wanted.
Now a few facts.
First of all, at no time I was mentioned officially that this series was yuri or Girls Love or nothing like that, simply described as a series that was about stretching and two girls living together, nothing more.
Second, Yawaspy is simply a seinen magazine and I know so far they have never published yuri or something like that. Prism on the other hand was published in Tsubomi, a magazine dedicated to yuri
Third, the way Shou ended Stretch is nothing new. In Gift, the first series of Shou, the main couple is separated at the end because the girl went to study abroad, besides that both series have similar style epilogues.
Fourth, if someone followed the rankings of the series in Yawaspy you may have noticed that most of the time Stretch occupied the first place and this implies that the series was well received.
Fifth, so I can understand it seems that the end of Stretch was received in a good way, based on the comments section of Stretch in Yawaspy or in some reviews.