Wait what do you mean by other timeliness please explain.
Where. Did you read the novel? Please share the link if you can pleaseee
it's a regression story, meaning ML regressed back in time. In the original timeline, he abused MC so bad (because he's an ass) which drove MC in original timeline to depression etc. So there's really only two timelines. One before ML's regression, and the one after, which the main story is following now, where ML is trying to atone for his actions in the og timeline.
Ido is anxious because this is around the same time when Sejin got raped by the brother (other timeline). He is the one behind his brother's missing, probably to prevent the same thing from happening.