Coming across pictures of your partner with an ex in their arms or on a romantic getaway on social media is an all too easy problem in the world of modern dating.
But experts claim it could be fuelling a problem called 'Rebecca Syndrome', with experts saying they have seen a rise in enquiries about the little-known condition.
Also called 'retroactive jealousy' Rebecca Syndrome refers to normal feelings of jealously but about things that occurred in the past, specifically your partner's previous sexual and romantic relationships.
Sufferers may compare themselves to their partner's ex and believe this past lover is better looking, smarter or even better in bed.
Although you may have never heard of 'Rebecca Syndrome' you may know the Gothic novel it's named after.
Daphne du Maurier's 1938 novel 'Rebecca' follows a young woman who marries a wealthy man. But after moving into his home she find herself unable to cope as the household and local community are still devoted to his late first wife, Rebecca (image from Netflix adaptation of Rebecca)
Sufferers may scroll through social media, looking at pictures and compare themselves to their partner's ex and believe this past lover is better looking, smarter or even better in bed
Authored by Daphne du Maurier in 1938 'Rebecca' follows a young woman who marries a wealthy man.
But after moving into his home, she finds herself unable to cope as the household and local community are still devoted to his late first wife, Rebecca.
Dr Darian Leader, a psychoanalyst and founding member of the Centre for Freudian Analysis and Research in London, took inspiration from the novel and coined the term Rebecca Syndrome to refer to retroactive jealousy.
But this syndrome is not just a work of fiction, with many people admitting to being plagued by these illogical emotions.
Psychotherapist Toby Ingham, who has written about the condition, admits he's had an increasing amount of people enquiring about Rebecca Syndrome since 2018.
Mr Ingham believes the rise in enquiries is due to people Googling and self-diagnosing their 'obsessional problem', which he stresses is 'not a good idea'.
While all of us can get jealous, some people get obsessive and even just the thought of their partners ex can cause them to spiral (image from Netflix adaptation of Rebecca)
Psychotherapist Toby Ingham , who has written about the condition, admits he's had an increasing amount of people enquiring about Rebecca Syndrome since 2018 (image from Netflix adaptation of Rebecca)
However, he explained that rather than being caused by relationships directly, retroactive jealousy often has it roots in childhood.
'While these early problems will be unique to each of us, they may, for example, relate to our having felt overlooked by a parent who preferred one of our siblings to us,' he told MailOnline.
'Or perhaps to problems feeling we were unimportant or excluded in our birth family.
'The problem is that we tend to lose sight of those early experiences and instead, we project the issues onto our present relationship.'
This can leave people 'vulnerable' to feeling as though they are being 'pushed out' or 'excluded' again, when it is often the case that they are not.
'We become too caught up in our projections to recognise the difference,' he explained.
One systematic review in 2017 of 230 studies on romantic jealousy found it was often rooted in low self-esteem and past experiences of infidelity.
Studies suggest jealousy in a relationship is relatively common.
Research in 2017 study on married couples in relationship counselling found 79 per cent of men and 66 per cent of women confessed to being jealous.
While not a problem in itself it can potentially rigger relationship issues.
But there's good news if you suspect you might be suffering from Rebecca Syndrome with Mr Ingham saying there are a few ways to tackle it.
'Ask yourself whether your anxiety, your intrusive thoughts about feeling less important to your partner than their former partner, may really relate to your own past rather than it being anything to do with your current relationship,' Mr Ingham said.
He also stresses the importance of refraining from scrolling through your partner's old social media feed as this can just unleash Pandora's Box.
While it may be tempting to look back on old pictures, including those with their ex, this will only exacerbate feelings of jealousy and make it easier to fall into negative thought patterns, he warned.
Another 2018 interview-based study found social media may encourage retroactive jealousy as you are more readily able to check details of your ex's past relationships.
For the same reason Mr Ingham also urges people to not to ask too many details about their partner's past that they may regret learning the answers to.
'Don’t ask about your partners past, particularly their sexual histories, oversharing at the start of new relationship often comes back to haunt us,' he said.