They are very much in love (with each other).

他们在热恋中。

So in love (so in love)

在热恋中（那么的爱着）

Grace and Henry are obviously madly in love.

显而易见，格蕾丝和亨利正处于热恋中。

Beware of people in love. for they are also insane!

小心那些热恋中的人，他们都是疯子。

Im in love with a boy and its a crying shame.

我与一个男孩热恋中，可是这档事令我懊恼不已。