Board Thread:Character Discussion/@comment-5834856-20140515094912/@comment-15736398-20140519210944

Marian explicitly says that her family believes she is dead, which is the entire reason Emma makes the decision she does re: taking Marian with her and Hook into the future, so we can say two things conclusively:

1) Robin genuinely believed Marian was dead PRIOR to Marian ending up being captured by Regina's guards

2) Had Emma not brought Marian into the future, Robin would have never known that the events that he believes caused her death didn't actually cause her death and that she died some time later