When she was young, Shirley had always thought that love was a happy thing, but now she knew that it was sad as well. She had dreamed of a life with Senel from the day she met him, but now she had gotten that life in a way that she never wanted. She had tried to be more than the girl he saw as his sister, but the more she tried the more he could never be hers.
He would whisper in her ear at night to comfort her, but she knew it wasn't for her sake. She would call his name and hold his hand, but that feeling of guilt never went away. And all the while he protected her, even though he was never supposed to, but Shirley couldn't fool herself to think he was beginning to care for her. It was just that Senel had nothing left to hold on to.
It had been silly, at first; she fell for the same boy that her elder sister would come to love, and they would engage in a tug-of-war over him that he was oblivious to. But Stella had always been kinder than Shirley, and now she had destroyed herself for Senel, and he loved her all the more because of it.
As for Shirley — she was the girl who remained. She was the girl who couldn't match her sister's selflessness, and in the end she was just a pitiful girl whose jealousy was going to make her miserable. Sometimes she thought he was suffering, too, but Senel never talked about it to her. They probably weren't very good at pretending to be siblings, she thought, since they were more distant with each other than ever before.
And the more time passed, the greater that distance grew. She tried — really, she did — to reach out to him, but his was a shield that could only be broken with the touch of his Stella, and she was not her.
But Shirley couldn't help but think. Living with him, looking at him, and loving him had all made her sad in the end, but was he really the one who couldn't let Stella go? Her sister's name and memory lingered not just around Senel but around Shirley herself. It separated them, but neither of them could let down their defenses, and Shirley wondered when she had started to see her sister as a part of him.
I wanted to write something for Shirley before she came to the Legacy, since I think she and Senel both were fairly miserable during that time, and they both were affected by Stella's "death."
I think Shirley didn't think that Senel loved her at all and was only looking out for her because of Stella, and it seemed to me that she felt like she was taking advantage of her sister not being there so she felt guilty for that, but she couldn't stop herself from being in love with Senel and trying to win him over.
Hopefully I was able to portray that situation pretty well, and I'm sorry this is so short.