"Let No Man Put Asunder" takes place on March 12. In this episode, Demetri tries to move up his wedding to this date but is kidnapped by Dyson Frost. This explains the title of the episode.
But in "Gimme Some Truth," we find out that March 12 is Mark and Olivia's anniversary. We find this out because Olivia wants to use the date as the access code to their alarm system. Despite Aaron workign on the system, the code doesn't work for Olivia. In the same episode, she gets an untraceable text saying Mark was drinking in his flashforward.
So, Demetri is kidnapped on Mark and Olivia's anniversary by Frost. And the date of their anniversary will not work on their alarm system.
You think there's something to this?