to seek out a new romantic partner, typically after a previous relationship has ended or when moving on to someone new

既然你们已经分手，你完全可以放下过去，另觅新欢。

to seek happiness elsewhere as a euphemism for engaging in extramarital sex; to find a bit on the side

他背着妻子在外面另觅新欢，这种行为导致了家庭的破裂。