You may watch below the US trailer of The Other Man, a movie in which Liam Neeson plays the role of a cuckold:

THE OTHER MAN

What if the one thing you cherished…
You lived for…
vanished
How much would risk?
How far would you go?

Plot;
“Peter (Liam Neeson), the CEO of a computer software company, has been married to Lisa (Laura Linney), a successful shoe designer, for well over 20 years. Her work means frequent travel, but their marriage seems happy, and they have a grown up daughter, Abigail (Romola Garai). Missing his wife, Peter discovers that she has been receiving emails and messages from a man he never knew existed.
Against Abigail’s advice, feeling betrayed and vengeful, Peter flies to Milan to find out the truth about the mysterious other man, Ralph (Antonio Banderas). As Peter begins to unravel his wife’s secret, the focus shifts to a suspenseful cat and mouse relationship between the two men.”

Cheating a sad thing, but no as much a big deal as movies would let us think… hey, life is short, no time to waste on that: if there is no more love on one side, better to let it go! So many potential partners in a life.
;-)