Psychologists suggest there are five stages of love - butterflies, building, assimilation, honesty and stability.
Each of these stages has a different impact on our psyche and health, researchers at eHarmony found in a 2014 survey.
Marked by intense infatuation and sexual attraction, symptoms noted by couples included weight loss (30 per cent) and a lack of productivity (39 per cent).
Biologically, it's reported that during this early stage of dating, both men and women create more of the sex hormones testosterone and oestrogen.
As a result more than half - 56 per cent - noted an increase in their libido.
Psychologists suggest there are five stages of love - butterflies, building, assimilation, honesty and stability
As the initial attraction gives way to learning more about one another, the honeymoon stage subsides and a couple begin to build their relationship.
eHarmony's study estimated around three per cent of Britons in relationship are currently at stage two.
The body releases neurochemicals called monoamines, which speed up heart rate, trigger rushes of intense pleasure and replicate the effects of Class A drugs.
The biological effect culminates in a feeling of 'happy anxiety', where people can think of little else than their blossoming relationship.
Forty-four per cent of the study participants noted a lack of sleep while 29 per cent reported a their attention span had been adversely affected.
Having established whether the other person is 'right', stage three forces a couple to question whether the 'relationship' itself is right.
Questions over the future of the union and forming boundaries in the relationship can lead to a rise in stress levels, reported by 27 per cent of those taking part in the study.
Each of the five stages of a relationship has a different impact on our psyche and health, researchers at eHarmony found in a 2014 survey (stock image)
Stage three combines with stage four, where people open up showing the 'real you' sees the first real rise in stress levels and anxiety.
'This stage deals with the concept behind how we all put on our best faces, through social media we edit our lives as well as our pictures to make it appear as though everything is fine,' psychologist Dr Linda Papadopoulos, who assisted with the study, told MailOnline.
Opening up completely triggered feelings of doubt and increased vulnerability in 15 per cent of participants.
If a couple can weather the emotional rollercoaster of the first four stages, the fifth and final stage, stability, brings with it increased levels of trust and intimacy.
eHarmony found 50 per cent of respondents had reached this stage, and 23 per cent reported feeling happier as a result.
Biologically, vasopressin - a powerful hormone released by men and women during orgasm - strengthens feelings of attachment.
Meanwhile oxytocin - released during childbirth - deepens feelings of attachment.
'This is where we see a real level of contentness,' Dr Papadopolous told MailOnline.
'We found the body releases wonderful hormones which helps couples bond. We noted a real sense of attachment, and a sense of "you have got my back and I've got yours".'