[1][2] When "homewrecker" is used to describe a person, it is applied to someone who breaks up a pre-existing relationship by having an affair with one of its partners.
It may be applied more often when the person actually intends to cause the break-up in order to replace the prior partner permanently.
[1] Other common targets for homewrecker labeling are intense pursuit of a career, devotion to a hobby, or running a business.
[3] The time commitment to these and similar activities can rend normal home life asunder and earn the name "homewrecker".
For example, in a faltering marriage, an estranged husband may have an affair, and the wife may blame the alleged homewrecker for the breakup of the marriage, even though the affair itself was partly the result of stresses that pre-dated it.