Such words are only used to fool unsuspecting, naive young girls. Even if a man says them to you, I advise all my female sisters - don't believe them!
Although Su Chaoyang is still young, his mind is mature. He's willing to spoil his cherished girl, but he won't do so without limits or restraint. He said what he did just now solely to discourage Du Mengxin.
So, when facing Mu Xiangwan's "trap" right now, he added a prerequisite. It wasn't because he was afraid that he couldn't do it, but rather he didn't want to weave unrealistic dreams for her with fanciful talk.
Happiness always favors the down-to-earth people, he believed that they would be very good together, more and more in sync, more and more matched, it just needed time to prove it.