cuz he thinks he will present as an omega which he thinks that the ML hates very much and rn they are currently tgt so once he presents as an omega, their relationship would end but everyone knows he's worrying for nothing lmao
Nahhhh you're just skipped chapters bro.. read it back
Pretty sure it's actually because they said at the beginning of the story that men almost always present as alpha and women as omega, and it's biologically impossible for alphas to be attracted to other alphas and omegas to other omegas. So they think that come December when he presents as alpha, that'll be the end of it since they'll both be alphas. (tho of course we know he'll be an omega and then get angsty about it for the reason you described)
why did he say that they were going to be friends in december?