Unless you have some inside confirmation from the devs that says otherwise, it looks like the there is a path for Jenna and Katie (+Jolina?). The MC tells Jenna about fooling around with Katie, and she seems open about sharing the MC with Katie (and looking at the code, it looks like Katie is added to Jenna's group). Obviously, we don't know yet if Katie will accept it, but this update lays the ground for it. There is also the alternative of telling Jenna about Debbie and Lilly, and she seems ok with them as well. But it also looks like (currently at least), Katie's path is mutually exclusive with Debbie/Lily (as far as Jenna is concerned), and you can only tell Jena about either Katie, or Debbie and/or Lilly (and Jenna being eventually ok with it).
There's also this code in e21 that solidifies what I am saying above: