Sometimes, the best thing in a relationship is to get out while you still can - and before you hurt each other too badly.
But what are the signs that you should cut your losses and run?
Several scientific studies have shown a link between certain behaviours - and either partner unhappiness, or relationships hitting the skids.
Either way, if you recognise any of the key signs below, it might be time to have a long, hard look at your relationship.
Does your partner ignore you to look at their phone?
If your partner ignores you to look at their phone - even when you are talking to them - it could be a sign your relationship is going south.
‘Phubbing’ your partner, ie snubbing them to look at your phone (‘phone’ plus ‘snubbing’ equals ‘phubbing’) is a relationship killer, according to Baylor University, Texas researchers.
It can also lead to depression, the researchers believe.
The researchers interviewed 145 people and found that 46% had been ‘phubbed’ by their partner and that, of those people, 37% felt depressed.
Dr Meredith David, ‘In everyday interactions with significant others, people often assume that momentary distractions by their cell phones are not a big deal.
‘However, our findings suggest that the more often a couple’s time spent together is interrupted by one individual attending to his/her cellphone, the less likely it is that the other individual is satisfied in the overall relationship.’
Do you feel you can talk to your partner about sex?
If the answer is, ‘No,’ it could be a sign that the physical side of your relationship, at least, is on the slide.
Researchers analysed data from 38,000 people from an NBC News survey, looking for common factors among couples who described themselves as sexually dissatisfied.
Around 60% of people who are dissatisfied with their sex lives, tend to agree with the statement, ‘I feel that my partner doesn’t know how to excite me.’
This hints that the key factor is talking about your sex life - and trying new things, according to lead researcher David Frederick of Chapman University.
Is your relationship full of drama and ups and downs?
Oddly enough, couples who argue a lot aren’t always the most likely to split up - the really bad sign is dramatic couples where there are constant ups and downs.
A study led by Brian Ogolsky from the University of Illinois found four distinct ‘patterns’ in the way couples interacted over a nine-month period.
Ogolsky says there are four ‘types’ of couple - dramatic couples (34%), whose relationship goes up and down, conflict-ridden couples (12%), who often argue, partner-focused couples (30%), who spend lots of time together and focus on each other, and socially involved couples (19%), with a lot of interactions with family and friends.
Ogolsky found, surprisingly, that conflict-ridden couples AREN’T the most likely to split up - it’s the dramatic couples.
Overall, Ogolsky found, stability is the greatest predictor of whether a relationship will work - couples with a lot of ups and downs over the nine months of the study were the most likely to end up separated.
Does your partner seem to expect you to behave badly?
If your partner expects you to behave badly - such as by being selfish, or short-tempered - it could be a sign the writing is on the wall.
Mathematician Hannah Fry - author of The Mathematics of Love - believes that if couples react negatively to each other all the time - for instance by dismissing or ignoring what the other says, the entire relationship can be poisoned.
Fry says such negative relationships hit a ‘tipping point’. She says, ‘In relationships where both partners consider themselves as happy, bad behaviour is dismissed as unusual.
‘In negative relationships, however, the situation is reversed. Bad behaviour is considered the norm.
‘A husband, for instance, might think his wife’s grumpiness is ‘typical’, due to her 'selfishness’ or other negative personality trait.’
Does your partner never say, ‘Thanks’?
If your partner rarely - or never - says, ‘Thanks’ for the things you do for them, it could be a sign that your relationship isn’t going to last.
Researchers at the University of Georgia interviewed 468 married people - and found that gratitude was a key ingredient in making marriages work.
‘We found that feeling appreciated and believing that your spouse values you directly influences how you feel about your marriage, how committed you are to it, and your belief that it will last,’ said professor Ted Futris.