What is a sunset clause exactly, AndrewP?

(You know, as the lesser earner who is 1 year short of that formula at this time...)

BD#1: "marriage is over" 9/14/2016
H in basement 24/7 with EX/OM
BD#2: 3/20/2017 I plan to move out "soon" I LRT
me: 42, H, 41, EX/OM, 37
D 10, Son 7
M to H = 20 years
EX/OM moved in 10 years ago