Board Thread:Show-Related Questions and Answers/@comment-5834856-20141112121124/@comment-5051564-20141119130809

I think Forget Me Not is an episode in which actually a lot of time passes (like Skin Deep. Belle spents months in Rumples castle), maybe Will spent months with the merry men too between the night he got accepted as one of them and the night he stole from Maleficent and got 'fired'. And if I remember correctly, at the start of Forget Me Not, Will got accepted as a merry man, but maybe he has trained / spent time with them / whatever, before that moment. So I think before / between the events of that episode, he got to know Marian.

Robin must have known Marian when Will was a merry man, because during that time Robin told Will a thousand times about how he and Marian met. (I'm assuming Will and Robin didn't catch up after the Maleficent-thing)