他们是男女朋友 英语怎么说

这句话有多种翻译方法，但是侧重点各不一样。

They are lovers(是说他们是情人）这个比较符合原句的意思。

They are in love/They fall in love(他们恋爱了）体现恋爱的事实。

He is her boyfriend/She is his girlfriend.(不用说了，主语是重点，后面是配角）

看你选哪个更喜欢。

they have been together.

they are an item

They are a couple.
我支持~~

They are close lovers.

They are a couple