The Prince of the Night and the Princess of Love are considered a couple in the public eye.
And this is only partly true.

Lilac and Flurry do care about each other a lot. They're both in an open relationship with each other and their other partners.
It started as a passing comment from Lilac's mom Autumn Blaze. The two heirs spent a lot of time together and Autumn is a big silly shipper.
The two didn't oppose it at first and started dating. The public LOVED these two together and they began to feel a little pressure to stick together longer than maybe their romantic relationship was meant to last. They still experiment together and have a more platonic love for each other but romantically they love other people.

Flurry is in love with her Royal Chef Pumpkin Cake and Lilac has a complex love-hate relationship with his demon shadow Eblis.
They are all relatively close friends and are keeping up the facade for now in front of their families and the public!