Dominic Monaghan knows what its like to feel lost.

The actor opened up about his devastating split with former Lost co-star, Evangeline Lilly , in his most candid interview yet about the breakup.

I think Ive only really got my heart broken once in my life, the actor said of his relationship with Lilly, during an appearance on Anna Faris podcast, Unqualified , in an episode published Wednesday.

I dont really know how she would explain the narrative, but from my point of view, it was probably the first time in my life that I was all in, the Lord of the Rings actor said, adding that the two were exploring kids and marriage during their relationship, which took place in the early aughts.

Monaghan explained that Lillys alleged infidelity and his issues with substances likely contributed to their breakup. HuffPost reached out to a representative for Lilly for comment.