I saw a review of the New York City production of this play, and since I can't travel to New York City right now (or back in time to see the original London production) I figured the next best thing would be to read the play. All four actors who have played these two characters are ones I really like, so I figured I could visualize it fairly well.
I love this play. There are all sorts of tangents, different possibilities a story can take, and this play explores them. Roland raises bees, Marianne is a career astrophysicist, and they meet, fall in and out of love, make life choices in all different permutations. There were times where they were heartbroken, others angry, others just not in the right place at the right time. Other times they were. Other times one of them would move one, other times they wouldn't. It was an amazing combination of what-ifs that could have fallen flat in some stupid way, but there was so much emotion just in the dialogue that it carried over well. It's experimental in a good way, in a way where it actually makes me think about all the ways that we assume stories, in our lives and in literature especially, are predefined when they really don't have to be (and not in a lame "Groundhog Day" and derivative works way). I read it when I was super sick and usually take even less of this quantum physics alternative timeline gimmick then, and it was awesome.