Word for the day you have spent half of your life with someone

My wife and I are approaching the point in our lives where we have been together for longer than we haven't. I was born in 81, she in 82 and we got together in 2000. I'm planning to celebrate the exact date this happens for each of us.

Is there a word for the landmark date where days prior to the start of a relationship becomes less than days in the relationship?


Solution 1:

As mentioned in the comments, half-life anniversary can be used.