A delusionship is an informal term for a romantic relationship that is characterized by one or both partners having significant delusions about the relationship. Some key aspects of a delusionship include:

• One or both partners imagines the relationship is much more serious or committed than it actually is. For example, someone believing they are in a fully committed, exclusive relationship when the other person is just casually dating them or even considers them a friend.
• Unrealistic expectations about the relationship or the other partner. This could include beliefs that the relationship is destined to be perfect, that the other partner will change in major ways, or that the relationship will lead to major life changes like marriage despite little evidence to support those beliefs.
• Ignoring, downplaying, or rationalizing away significant problems, conflicts, values differences or warning signs that the relationship is troubled. This allows the delusions about the relationship to be maintained.
• Projecting idealized fantasies onto the other partner rather than seeing them realistically. This could include believing someone is "perfect" or your "soulmate" when you actually know little about their real self.
• Envying relationships that seem happy from the outside while being unable to evaluate your own relationship properly or acknowledge its flaws.
• Staying in the relationship for too long despite clear evidence it should end, often due to being overly attached to the fantasy of what you wish the relationship was rather than what it truly is.

In summary, a delusionship refers to a romantic involvement where one or both people are fully committed based on serious delusions, rather than realistic assessments, about the relationship. These delusional beliefs allow them to stay with partners who are incompatible, uninterested in commitment.