Just as >>98488427
said, the term has been beated to death as a Be-all-end-all insult and lost its normal meaning to most casual people, loosely connecting it to cuckoldry because husband is "letting" his wife be fucked by other man, even though he is not.
Most NTR stories revolve around blackmail, persuasion or unsatisfaction>Blackmail
Husband may have done something DISHONORABURU or wife had one slip up nad had a one night stand, but the 'stealer' had taken evidence of the act and uses that to blackmail wife into sexy times.>Persuasion:
Family is having hard time finacially. Company may be firing hubby to save on money. Boss of the company or shareholders need to be talked away from firing the hubby and the only way that they would let him be is by having sexy times. This may also tie to previous segment and escalating into fetishes>Unsatisfaction
Usually the more common one. Wife cant sate her sexual needs and by random occurance gets to a one night stand that turns into more stands because that new cock is so much better than hubbys. Guy doesn't have to bootycall her. She goes to him because she needs it so badly.
All scenarios have the wife being desperate in the appropriate meanings. She is not doing it to spite her husband. She loves her husband with all her heart, but things get out of hand. She becomes addicted to the pleasure, maybe even loses her love for hubby in the process, and thus is "stolen away by sleeping with"
NTR is not cuckoldry, idiots.