I dont think Sid thinks that he was used. He knows very well that he can't be used unless he allows it himself.
I am worried that Sid is controlling his emotions as he is not used to people like Sana in his life. Sana has toppled his life upside down and he can't control it however hard he tries.
Question: Why did he ask Sana to change her bed? Why didn't he do it himself? Well first year marriage is very tough😆 this was just to lighten up the mood.
he did think he was used, go back to his talks with Vikas and his talks with Paras during cat and mouse task you will know
And he saying Sana yesterday, I used you was all of that