When he was with Du Mengxin, he had noticed her feelings for his brother. But, love blinded him so much that he chose to ignore that 'awareness'. Unfortunately, ignoring something doesn't mean it ceases to exist.
During that period, he was trapped in love, he even resented Su Chaoyang for meeting Du Mengxin so early, yet not choosing to be with her.
In his heart, he unquestionably presumed Du Mengxin to be many times better than Mu Xiangwan. At that moment, he even thought that even if he couldn't have Du Mengxin, he would still wish for her happiness.
He even considered disrupting the relationship between Su Chaoyang and Mu Xiangwan, hoping Su Chaoyang would accept Du Mengxin.
Looking back, he now thinks how grand he was back then! Grand to the point of being appalling!
The thing he felt relieved about was that his last bit of sanity managed to control his rampage, preventing him from doing something he'd regret more in the future.
He also resented Mu Xiangwan.
