Oh yes, it's a totally appropriate
The thing is, while everyone is drooling over ALOK ep.10, my current ATLA rewatch got me shipping Tokka. Hard.
Those two are almost as cute as Zuko himself (who is nearing divine, if we can say 'divine' about a cartoon character).
In ep.4 of b.3 Katara blatantly states Toph gotta marry Sokka. All doubts cleared.
Toph & Sokka © Michael Dante DiMartino & Bryan Konietzko. NOTE: about Lin/Tenzin dating
they probably stopped dating after Lin discovered who her father was... I'm inclined to believe she never knew Sokka was her father, and when she and Tenzin decided to marry, Toph revealed the family secret. Which made Tenzin go seek consolation from Pema. Heck, poor Lin