Rupphire

Garnet is a fusion of two non-binary romantic partners, Ruby and Sapphire, from Steven Universe.

How they met...
In the episode "The Answer" in Steven Universe, Garnet (a fusion of Ruby & Sapphire) reveals to Steven how Ruby and Sapphire met.

Homeworld gems were in the process of colonizing Earth but 'The Rebellion' or better known as 'The Crystal Gems' were determined to halt the process. Sapphire was summoned by Blue Diamond to report to Blue Diamond about what would happen to the rebels-because Sapphire had future vision-so along with Sapphire they sent three Ruby bodyguards. Sapphire informed Blue Diamond that the rebels were going to attack the Cloud Arena, resulting in the poofing of seven, three of the gems would be two of Sapphire's Ruby guards and Sapphire herself and then the rebels would be captured. The attack was right on time revealing the Crystal Gems to be Rose Quartz and Pearl. The attack was just as Sapphire had seen but when Pearl advances on Sapphire, Ruby could not accept it, Sapphire had known Ruby would fail so she jumps in front not only saving her but also involuntarily fusing into Garnet. The homeworld gems crowd the rebels, glaring in anger at both the rebels and the fusion(as they had never seen a fusion of two different types of gems before). The rebels flee the Cloud Arena. Then the homeworld gems cluster around Garnet who instantly unfuses. Blue Diamond becomes displeased about what had happened as to that was not what Sapphire had foreseen, but Ruby takes the blame. Blue Diamond sentences Ruby to be broken-referring to breaking her gem-as the homeworld gems start to crowd around then almost immediately Sapphire takes Ruby's hand and sprints away, jumping down to land.