Chart explains Dr. Who-River Song relationship

A kiss is just a kiss, except ...

You've heard of family trees? Well, this one is more complicated than most and it involves just two people.

BBC America is reporting on "Meeting in the Wrong Order," a chart that details the relationship between Dr. Who and the woman who loved/killed him, River Song.

To say the least, it's complicated. Click on the link above to get an enlarged version of the graphic, which traces their story from conception to ... the end?