Delusional disorders are characterized by bizarre (implausible) or non-bizarre (mistaken but not impossible) delusions that persist for at least one month.
A person suffering from erotomania has the non-bizarre delusion that another person, often a stranger, is in love with them and that they are destined to be together. Consequently, they will obsessively talk about that person and attempt to make contact by whatever means possible, and even when the other person cannot or will not reciprocate, this is understood as further proof of the necessary “secrecy” of their reciprocal love.
The object of fixation is typically someone of higher status such as a celebrity or someone of great standing, authority, attractiveness, or wealth. Indeed, the person who is the object of these delusions may not have had any interactions with the person suffering from the delusions.