Therapist shares science behind why people in long-term relationships have less sex

A therapist has shared a reason why people can stop sleeping together so much in a long term relationship.

We all know the honeymoon phase - you meet someone, they're amazing, you've never felt this way before about someone, and then to make things even better, they feel the same way about you.

What follows is a sweet spot, where you can just get lost in each other, and the realities and daily grind of life are pushed aside, for a bit anyway.

Imperfections are endearing, and you haven't gotten to know each other so well yet that you settle into a routine, or feel constricted. Everything is easy with them.

Also sex. Lots and lots of sex.

It goes on for a few months where scarcely a day goes by without tearing each others' clothes off, getting into all manner of acrobatic positions, and not a room in the house unused - just don't tell your flatmate about that time on the kitchen counter.

Things can really get off with a bang (Jackyenjoyphotography/Getty)

But as the months go on, things start to fizzle. You're still affectionate, but it's not the same wild abandon as it once was. So what happened?

Many people assume it's routine, or familiarity, or even just getting bored. Those habits that were adorable are now annoying, you're both tired, or not in the mood.

But somatic therapist Briony Montgomery has a different theory, and it suggests that this might even be a good sign for the relationship overall.

She told Body+Soul that the theory is that when you begin to feel completely safe with someone, it actually makes you feel less desire.

This is because your body, which had previously been checking for unfamiliar and potentially dangerous things, now has nothing to detect, but is still scanning, making you feel less inclined to get it on.

“When your body is constantly scanning for what might go wrong, it’s very difficult to drop into pleasure,” she said.

Things can sometimes cool off (Maria Korneeva/Getty)

So this is the theory, but how can people get around this problem and keep their sex life going?

Good news - Psychologist Taash Balakas suggests allowing yourself to feel safe in the relationship, because this counters that anxiety.

You may understandably be worried about someone leaving, or worse, or relying too much on one person, but allowing yourself those things gets rid of that anxiety, and makes for a more romantic atmosphere.

“Softening doesn’t mean losing your independence,” she told VICE. “It means allowing yourself to experience care without assuming it will disappear."