>>42390491
I know their relationship wasn't established much in unicorncon its just where it started.
The episodes where you really see their relationship growing after Unicorn con are
>Soarin and Braeburn movie
Where the mane 6 tries to abandon twilight and twilight calls them out while Rarity has her back, also Rarity is the one to help Twilight stop feeling so sad when she realizes her friends are avoiding her.
>"What about you Rarity? What you got" - Twlight
>"Oh you know I love you girl" - Rarity
It progresses further a bit in Applejack and Rarity leaves
Then further in Twilight fights a clown where she shows up at Rarity's taco tuesday.
Then even more in lemonade stand.
Then its further established in Hotel episode, then its formally solidified in the Outbreak movie.