Many relationships go through ups and downs, but only some of them are going to stand the test of time.
And because we don't have a crystal ball to look into our romantic future (as much as we would like one), we've called on science for some good old-fashioned evidence that our relationship is as good as we believe it is.
So here are seven signs that you are in a happy place with your partner.
1. You have had previous long-term relationships.
No one likes to dwell on past relationships when you're busy falling in love with someone new, but it turns out it might help our new endeavours.
According to relationship expert, Dr Jacqui Gabb, those of us who have loved and lost shouldn't "lock that experience away in a cupboard". Instead we should learn from those experiences, picking up on relationship warning signs and learning who to hold on to.
2. You met each other on Tinder.
...or any other online dating app for that matter.
A study found that couples who met online, rather than at work or in a bar, are more satisfied with each other and less likely to break up.
The study said: "This data suggests that the internet may be altering the dynamics and outcomes of marriage itself."
3. You don't post annoying photographs on Facebook.
As much as it might seem really tempting to post that #couplegoals selfie on Facebook, a study has found that those who don't post their relationship all over the internet are the happiest.
This is because they aren't anxiously seeking other people validate their romance. So remember that fact next time you're picking out the best filter to optimise your smugness.
4. You enjoy watching Netflix together.
It's Friday night, and you've settled down with a takeaway and a night in front of the television for the third week in a row. While it might not feel like you're living your best social life, watching boxsets and movies is "good for relationships" and for your health, according to researchers.
This is because it supposedly enhances the quality of your time together (they clearly haven't seen you arguing over GOT plot spoilers).
5. You make time to pay them compliments.
Everyone likes to hear nice stuff said about themselves, but in a relationship things can easily get a little stale and forced on that front.
So you'll be pleased to hear that science wants us all to pay a few more compliments and say "thank you" more often, as it is one of the most important factors in keeping a relationship healthy across all groups.
6. You have sex once a week.
If you're worried everyone is getting between the sheets more than you, then you might be comforted to know that the optimum amount of sex for a happy relationship is just once a week.
While having an adult sleepover more than once a week doesn't hurt, it also isn't making a difference to your happiness levels, so you might want to conserve your energy.
7. You do not have any children together.
Although this may not be the plan forever, you should enjoy your childless years, as one of the biggest ever studies of relationships in Britain revealed that if you want to be as happy as possible, you're better off not having kids.
Childless men and women are more satisfied with their relationships and more likely to feel valued by their partner.