You don't really have to Save the Date as it isn't really worth watching. Lizzy Caplan (Cloverfield, Bachelorette) stars as indecisive Sarah, who runs from her long-term relationship with a musician (Geoffrey Arend - 500 Days of Summer, Devil) when he decides to propose to her during the encore of one of his concerts. Sarah's sister Beth (Alison Brie - "Community", "Mad Men") is getting married and while she loves her sister they don't always get along (and Sarah NEVER takes her advice). We get an hour and a half of this as Sarah starts a new relationship with Jonathan (Mark Webber - For a Good Time Call, Scott Pilgrim vs the World) but then begins to question that too when he turns out to be "too good".
This is another tale of a thirtysomething struggling to figure things out ... and this could become a brand new sub-genre of drama. Save the Date doesn't really give an audience anything new to enjoy or appreciate cinematically ... we are just getting another version of this oft-told experience/story. As this one never rises above what we have already seen, it isn't anything to recommend (unless you really like Caplan of course ... whom I wish would get the perfect role someday -- and this isn't it!).
Thanks for asking us to Save the Date, but I will regrettably decline as there is surely something more interesting to watch.