When a romantic affair lacks both overt and covert sexual behaviour and yet exhibits intense or enduring emotional intimacy it may be referred to as an emotional affair, platonic love, or a romantic friendship.
An extramarital affair that continues in one form or another for years, even as one of the partners to that affair passes through marriage, divorce and remarriage, could be considered the primary relationship and the marriages secondary to it. This may be serial polygamy or other forms of nonmonogamy.
The ability to pursue serial and clandestine extramarital affairs whilst safeguarding the secrets and conflict of interest inherent in the practice, requires skill in deception and duplicitous negotiation. Even to hide one affair requires a degree of skill or malicious gaslighting. All these behaviors are more usually called lying.
Deception can be defined as the "covert manipulation of perception to alter thoughts, feeling, or beliefs". The presence of deception may indicate the degree to which the deceiver has breached fundamental conditions of fidelity, of reciprocal vulnerability and of transparency. Sometimes these are explicit or assumed pre-conditions of a committed intimate relationships.
Individuals having affairs with married men or women can be prosecuted for adultery in some jurisdictions and can be sued by the jilted spouses in others, or named as 'co-respondent' in divorce proceedings. As of 2009, eight U.S. states permitted such alienation of affections lawsuits.
Ben Ze'ef argues that an online affair is a unique kind of affair—termed "detached attachment", or just "detachment"—that includes opposing features whose presence in a face-to-face affair would be paradoxical. Like direct, face-to-face affairs, online affairs can be spontaneous and casual and show intensive personal involvement. However, online affairs can also be more of a planned discourse than spontaneous talk; like written letters, online messages can be stored and thus have permanent presence, which is absent from face-to-face affairs.
People participating in online affairs may be strangers to each other in the sense that they have never actually met each other. However, they are also close to each other since they share intimate information. In online affairs, people try to enjoy the benefits of both close and remote affairs, while avoiding their flaws. People enjoy the highly valued products of close affairs while paying the low cost of remote affairs. As one woman wrote: 'He constantly told me that he can not provide me with what I would want and I would always respond with: "I'm not asking anything from you, but simply enjoy your company".