Fiona is happily married to Elio. She enjoys the time she spends with him and wants them to have a future together.

However, she can't stop thinking about her coworker Brendon these days. She dreams about him at work and sometimes flirts with him a little when they're together during their break. But it doesn't occur to her to share her feelings with Brendon, and she certainly doesn't intend to tell her husband about them either.

However, she often has romantic fantasies about Brendon. One night, she even imagined making love to him while she was having sex with Elio. She felt a little guilty about it afterwards.

She is in her thirties, feeling the same as she did in her teens.

'Fixations' aren't just for teenagers

According to University of New Brunswick (Canada) psychologist Lucia O'Sullivan and her colleagues, obsessions are not just an experience for teenagers. On the contrary, adults of any age can have obsessions - even when they are in a committed relationship with their partner.

To clarify the discussion, O'Sullivan and her colleagues define infatuation as a one-sided attraction to another person, for which the experiencer has no intention of communicating or acting. In this way, it is distinguished from other types of romantic attraction, such as passions or mutual attachments.

How do single people differ from those in a relationship when it comes to 'fixations'? 

Researchers found that people in committed relationships reported significantly more 'flirting' than those who were single. At first glance, this may be an unexpected finding, but it makes sense upon further examination.

Singles are more likely to act on their attractions to others rather than letting their feelings remain in the ‘unrequited’ stage. The opposite is true for those in a relationship, who hold back from expressing their feelings for the sake of preserving their relationship. 

On the other hand, if we find ourselves acting on our own desires and showing our feelings, this is a sign that there are problems in the relationship. As the results of this study show, attraction alone is not enough to push a person towards infidelity. Instead, the research shows that it also takes the availability of the other party, as well as a deep dissatisfaction with the current relationship, to push a person to be unfaithful to their partner.

Along these lines, O'Sullivan points out that many adults maintain a threesome relationship, just in case things get out of hand with their current partner. 

In short, flirting and infatuation are a common phenomenon not only among teenagers but also among adults, especially those in committed relationships. The current study shows that they are mostly harmless, as they can relieve fatigue and even positively affect a couple's sex life.