Hmmm, while it does sound interesting, I don't think Odette would be with someone unless she really loves him. And as twisted as he may be, she would probably feel being with someone else is betraying Ben. 
Perhaps, we can kind of mix both of our ideas? Like, rather than her having a fling with him, the four of them (Rey, Finn, Poe, and Odette), have to go undercover on some planet and so they pose as two couples (Rey and Finn as one and Poe and Odette as another). Ben sees this and thinks its real. He flips out in jealously, tracks Poe down, and badly injuring him? Then we could do the pairing with him and Tatooine girl later on once he's recovered?

What I'm thinking is that, perhaps, after the attack and her being held captive in secret by Snoke, she escapes and heads back to Luke's temple in hopes of finding him. Only he has already run off in shame of what happened with Ben. She's searching whats left of the temple for some sign of where he could have gone, when she finds a piece of the map to the first Jedi Temple. Now she has three of the four pieces and just needs to find the last piece (finding a clue of where it is in some of Master Luke's writings). She is preparing to leave, when a ship lands on the planet. This ship ends up being Leia, Han, Chewy, and some of the other rebels. Leia, having lost contact with Luke and fearing the safety of her son, came to the planet to see what happened. They bring Odette off of the planet, where she tells them what happened. At the news of this is when Han leaves and Odette tells Leia her plans of finding the first temple and continuing to train, basically hiding herself away. She knows she's not ready mentally to face Ben and decides to train until she is. With that, Leia gives her a ship and Odette leaves with BB-11, leaving BB-8 there with her as a means of Leia finding her if need be. I figure her meeting Leia is a bittersweet thing for both, considering for Odette this is the mother of the man she loves, and for Leia, Odette is kind of like a daughter in law in a way XD I can also see Leia telling Odette that she knew of her and Ben, Luke having told her long ago about the building relations between the two Jedi.

I figure Odette finds the last piece of the map to the last Jedi Temple (perhaps the temple Luke was at in the Last Jedi was not the First Temple, but still a very old temple). She hides herself away there, continuing to train. I figure we could have Luke die in some other way than the disappearing thing XD Something more dramatic, such as him being killed by Ben or dying protecting Leia. And after Luke dies and Rey still needing to finish her training, Leia knows they have no choice but to reach out to Odette again, Leia and all of them going to where Odette is to convince her to help them. 

From there it'd be pretty open XD That's just my thoughts of how it could go. What do you think?