@geraldine08172006 They would have thought he was planning something! Normally in this situation, (losing the right to the throne) someone would be very upset, so he acted like he did not like the arrangement to avoid suspicion.
raw link: https://www.kuaikanmanhua.com/web/topic/5701/?Source=6&TimeStamp=2020-10-05%2006%3A27%3A12%3A192
novel raw link:
https://m.gongzicp.com/novel/index/id/17614