Years went by, Sweetie was fully grown, cutie mark and all. She had a job, she had a boyfriend, and she mourned the loss of the one she loved the most. Rarity had passed away after a battle with cancer. Sweetiebelle cried every day for 3 months after Rarity was gone... Until a stallion named Dusk Racer showed up. Dusk was always supportive... And then he asked Sweetie out. She accepted.
It was perfect from then on. Sweetie got her cutie mark as a painting on an easel, and Dusk got his as a sunset. They moved in together, and they were happy. Rarity would've wanted this; For Sweetie to settle down, get her cutie mark, and live a happy life.