ラブアフェア

noun

love affair

A romantic relationship, often with a connotation of being extramarital or secretive, similar to the English term.

• 彼かれは既き婚こん者しゃなのに、職しょく場ばの同どう僚りょうとラブアフェアを持もっているらしい。

  Even though he's married, he seems to be having a love affair with a coworker.