If the things in the Awaken cinematic are true....
In the Noxian invasion, at some point Riven gets taken back to Noxus and Yasuo is fighting with Kennen, Akali, Irelia, and Karma against Sion and an army of Noxians
https://i.imgflip.com/3o5wz2.jpg
Following this I always believed that the two would meet again, with Yasuo basically returning to the village to survey any damages, only to find that they had found Riven and carted her back to Noxus, leading to the following scenario
I always imagine Riven getting taken back to noxus like the scene from awaken and as she's being brought back Yasuo, realizing what happened decides to rescue her in an attempt to redeem himself as she had attempted to do, and ventures to Noxus undercover (likely with the help of Sett), and that right after the jumpcut of Riven and Draven going to attack each other, a loud 'Hasagi' is heard as Yasuo enters the ring sending the two combatants flying away from eachother. The duo fight their way out and make their way to Freljord with Riven having to constantly be on the run from Noxus now that they know shes alive.
Doesn't have to be lovey dovey or shit, just two people coming to better understand each other, and Yasuo learning to forgive himself after he succeeds in freeing Riven. They might travel together or might go their separate ways. Sure they could be like fck it edgy romance, but honestly if that were to happen that would be 1 way too soon and 2 a bit unnecessary.
Just let it be two warriors that have both gone through some shit and grown into better people for it with the help of someone going through a similar situation.
I feel like it would 1 get Riven out of being a indentured worker in Ionian fields, and 2 finally allow Yasuo to be something other than a man feeling sorry for himself.
This is of course just my thoughts on where their stories could go, what do ya'll think?