It's not that Wukong didn't want to marry Buma, but that Wukong didn't even know what marriage and love were at that time. If Wukong's head was completely damaged when he was a child, judging from their adventures, Wukong and Buma would probably be together. At that time, Buma's original purpose was to collect dragon balls, and Buma's wish was to have a handsome boyfriend. Although Buma didn't realize this wish in the end, the appearance of Yamcha made Buma gain something.