英语翻译从此,黑桃J王子和红桃Q公主过上了幸福、快乐的生活.要一字不差,最好有点浪漫（虽然貌似不可能）,像在童话结尾的那

The prince and princess lived a happy life ever after.（王子和公主从此过着幸福的生活） 这是标准的童话故事的happy ending model；套用到你的句子中：The Black Spade prince and the Red Peach princess lived a happy and carefree life ever after.
注：ever after 就是从此的意思,前面不必加 since then on!

Since then, a spade J the prince and princess lived red peach Q and happy life.

Since then,the spade J prince and red peach Q princess lived with a joyful and happy life.