In a complicated and decent era, men fell in love with women behind their backs.
Shen Ye×Xie Yi1.0→2.0
Out of consideration for the original work and a preference for heroes who deserved to be unsympathetic, Shen Ye had a crush on Cang Ming when he was a boy, and had an ambiguous relationship with Hua Yue throughout his life. However, this sentiment only applies to gentlemen, and the orthodox CP is still Shen Xie No doubt.
It's a completely fictional setting, and you can bring in whatever era and background you like, so there's no need to take it seriously.