True, but on the other hand, Sena doesn't complain.
If you think about it she doesn't have a reason to, the reason why she runs off is not because she is badly hurt, but because she is treated like a normal person and is overjoyed. It's pretty much one of the reasons why she joined the club in the first place. No matter what Yozora does to her, Sena keeps winning, which pisses Yozora to no end.
I do feel bad for Sena at time, but knowing that, I just laugh 
Finally someone who sees the show the same way I do. Everyone has been fighting about this on other forums and I just stay out of it because no one seems to understand the undertones of the show.
To me, Sena is trying to open up to Yozora, because Yozora actually interacts with her on a level beyond what others do. But while Yozora wants friends, she has a massive problem (phobia even) of interacting with others. So she puts up walls and becomes bitchy when someone tries to be nice or interact with her....which is what Sena is doing. Its pretty much an evolved version of the Tsundere cycle we've seen time and again in shows like Eva, Ranma 1/2, Love Hina, etc. Except this time its two girls going at it.
And of course Yozora is mad that Sena keeps getting attention from the main character, but Yozora is kind of doing it to herself. Every time she makes Sena cry, she goes and runs off to Kobato, who helps Sena feel better. Yozora is really her own worst enemy at this point. She wants to be friends with Sena and likes Kobato...but keeps pushing them both away.
