No, I would not encourage anyone to cheat.
The vast majority of cheaters are looking to hold onto all that is "good" in their primary relationship while addressing their other "needs" on the side. They want to "complement" what they already have.
Most cheaters aren't looking to (replace) one relationship with another one. Nevertheless there are some people who do treat relationships like jobs. They won't leave one until they have another one lined up.
If this person has no intention or desire to stay with her husband she might as well leave him without jumping through all the hoops of lies, secrecy, and stressing over being caught that cheating entails.
As I stated most cheaters (in their minds) cheat to (avoid) going through divorce! They don't really believe they will be caught!