"替她开心"在英文中可以用 "make her happy" 来表达。这是一个常用的表达方式，没有特定的来源。

下面是一些例句：

I want to make her happy. (我想让她开心。)
He always tries to make her happy. (他总是尽力让她开心。)
She loves to make others happy. (她喜欢让别人开心。)

另外，这个表达方式也可以改变为 "bring happiness to her" 或 "bring her joy"。例如：

I hope my gift will bring happiness to her. (我希望我的礼物能给她带来快乐。)
His words always bring her joy. (他的话总是能给她带来欢乐。)