The Cottagers have first option to retain the 29-year-old and Jol reiterated his intention to ensure Riether is part of his squad next season.
"Sascha is a fans' favourite," Jol told Deutsche Pressagentur. "He is the right-back in my starting XI.
"He runs, he works and he has a good view of situations. I am glad to have him at this club.
"We possess an option [to buy him]. If we are to exercise it, he will have to remain at our club. But if he is not happy, we would have to talk then.
"But I really don't think that this is the case with him. I think he feels fine being a first-team regular with us."