I read this as part of The Time Traveller’s Almanac, edited by Ann and Jeff VanderMeer.
In a future where one can travel back to the past, and where actions in the past change the reality of the “present”, what would you choose to do?
This story, from Nick’s perspective – he’s married to Janine – tells of how Tommy, Janine’s jealous ex, systematically travels into the past to destroy their marriage and get himself back together with Janine.
There are a few interesting elements to it. One is that, when a person’s reality is changed, they know it (it’s called phasing), and for a few hours (three max) they are able to recall the former reality. Another is that it is almost impossible to prove that one’s been phased – something that presents Nick with complications when it comes to confronting Tommy or working to prevent Tommy’s meddling.
Overall, an entertaining story of some complications that can arise from time travel.