“看了才知道，原来这是一部爱情片”中原来用英语怎么说 ？

after seeing it，I know that it's actually a romantic movie.

"Read only know that this is an original romance" in the original

不能这样逐字逐句的翻译英语的吧

indeed/ at last/ truly

Not until I had seen it, did I know it's a romance.
romance可以直接作名词，解为爱情片

that

因为你的这个是有语境的````所以承上启下,就用that就可以的!