Basically, kloff remember all the things he did to Aeroc in first timeline (s1) and try to redeem himself to Aeroc. While he also fall for Aeroc in this tl, he too, long for Aeroc in 1st tl to the point he become suicidal. Just like Aeroc feeling guilty in s2 & s3, we also get to see Kloff yearn for Aeroc's forgiveness in this tl.
(SPOILER ALERT!!! ----------
The guilt Kloff feels is real, just like s2 &s3 Aeroc feeling unworthy of Kloff's love, Kloff also feels the same in this side story. BUT, he is still a schemer just like in his first life. He scheme Aeroc's financial crisis so Aeroc would ask for his help. He pulled some strings and cut the others so Aeroc only have him to go to. The only thing he didn't expect in this life is that Aeroc will also manifest as an omega later late in the story.

So is this another timelines? I thought the side stories was gonna be cute and happy