I am so happy for you.我真为你高兴。
在英语中，常用I'm really happy for you. / I'm so excited. / It's so exciting! 之类的话表示祝贺。

Congratulations on your marriage! I'm so happy for both of you.

恭喜你结婚了!我真为你们俩高兴。

I'm so grateful for your kind words.非常感谢您的问候。
I'm grateful.的意思与Thank you.类似，即表示“感谢……”之意。其常用 搭配有be grateful for something 和be grateful to somebody。
Many thanks for your kind expression of sympathy.
对您的诚挚慰问深表谢意。
Thank you so much for your kind words and consolation.
非常感谢您的关心和慰问。