Duff and Koma have one child together, their six-month-old daughter Banks. The two were first rumoured to be dating in early 2017, People reports, although they didn't truly get back and stay together until later that year.
Duff has one other child, her seven-year-old son Luca Cruz, whom she had with her ex-husband Mike Comrie.
Duff talked to E! in December 2017 about how her and Koma's relationship was going, revealing then that it was on-off in the beginning. "It's going so great," Duff said of their status then. "I mean, this is the third time that we've dated and I think that what Selena [Gomez] says has so much merit to it. Timing is such a big deal…third time's a charm!"
WATCH: Hilary Duff Shares Video Of Her Daughter Banks' Home Water Birth.