Planning a holiday, driving each other's cars and having a key to your partner's flat are all signs a relationship has got SERIOUS, it has been revealed.
Researchers quizzed 2,000 people to reveal the top 50 things which indicate a couple are past the 'seeing each other' phase of a relationship.
Posting a 'loved-up' photo on Facebook, changing your status to 'in a relationship' and being introduced to wider friendships circles also show couples are the 'real deal.'
While meeting potential in-laws, staying overnight and divulging salary details also show trust and growing love for a partner.
And couples are usually together for just over five months before they deem the relationship to be 'serious'.
A spokesman for Monarch Airlines, which commissioned the study said: 'It's no longer just a case of talking about moving in together, marriage and children. There are smaller elements such as when to say I love you, when to stay the night, and when to swap house keys.
Other relationship milestones include meeting the parents, becoming the 'plus one' on all invites, seeing each other through an illness and comfortably phoning each other at work.
TOP 50 SIGNS IT'S SERIOUS
1. Meeting the parents
2. Exchanging house keys
3. Planning a holiday together
4. Discussing plans for the future
5. Being invited to family gatherings
6. Saying "I love you"
7. Staying overnight at each other's houses
8. Signing Christmas / Birthday cards together
9. Seeing each other at least every other night
10. Leaving a toothbrush at each other's house
11. You tell each other absolutely everything
12. Letting them take care of you when sick
13. Being introduced to wider friendships circles
14. Discussing how many children you might want in the future
15. Buying a dog or cat together
16. Driving each other's cars
17. Inviting them to a wedding as a date
18. Divulging salary details
19. Letting them know your pin number
20. Discussing holidays
21. Having a drawer at each other's house
22. When you HYPOTHETICALLY talk about IF you lived together
23. Inviting people round as a couple
24. Having clothes and other belongings at each other's houses
25. First name terms with their mum and dad
26. Talking about intimate health issues
27. Farting in front of each other
28. Inviting them out with your friends / family
29. Receiving cards or gifts addressed to both of you
30. When you know what each other's plans are for every single day
31. Showering together
32. Changing Facebook status to 'in a relationship'
33. You know each other's passwords
34. Wearing pyjamas when you get home from work
35. You share secrets about friends with each other
36. Always being the 'plus one' on invites
37. Getting food in your big shop just for them
38. You start watching TV shows they like
39. Phoning each other at work
40. Stop putting make up on to look gloriously fresh before they wake up
41. When they start asking for your opinion on stuff
42. Going out with friends or family without the partner being there
43. Signing off 'love' in a card
44. You start listening to music they like
45. You stop seeing people you know they don't like
46. Putting a photo of the two of you on Facebook
47. Sending good morning / goodnight texts
48. Having a pet name for each other
49. Telling each other how many sexual partners you've had
50. When all their friends add you on Facebook