The former Coronation Street star briefly split with the 24-year-old following reports that he had sent flirty text messages to another woman.
"I'm very picky," Flanagan told Now magazine. "I think that comes from having parents who've always been together. So I kind of think if you love someone, you have to sort it out.
"The time apart probably did us some good. We got together when we were really young – when I was, like, 19, so it's kind of hard. Scott's really good with me."
Sinclair is currently on loan at West Bromwich Albion.