When you both get naked- Once it was exciting to see your partner naked- it used to instantly turn you on- now it's not a turn off but you are so used to seeing their naked flesh you don't blink an eye when they wander in with their bits out.
When you come home- When you first started dating, you used to greet each other with a big snog and a cuddle and talked of nothing else but missing each other. Now you come in and nod in their general direction before heading to the fridge for a snack. They might get a peck on the lips if they're lucky.
When your partner cooks you tea- At one stage you used to think they were lovely for taking the time out to make it for you- now you just think 'it's about time- it's well and truly their turn.'
When you have sex- You know you're comfortable with one another when you go from having sex to resuming what you were doing before you begun- like looking at your phone or reading.
When one of you passes wind- At one point this would have been earth shatteringly embarrassing- now you congratulate each other on the strength of stench and the intensity at which it came out.
When one of you burps- Again- once upon a time you would have beaten yourself up for days at letting one out after dinner- but you've now gone from being bashful to boastful over your belches.
When you see each other's parents- You would never have dreamt of slagging your partner off to them or showing them your real mood at the beginning of your relationship. But now you treat your parents in law like your own and tell them like it is- no holding back.
When you have to 'go'- When you first got together talking about poop was as controversial as talking about sex in front of your parents. Now you warn each other to 'give it five' or tell them where you're going and what you will be doing so they give you some undisturbed time to evacuate your bowels while reading post or looking at your phone.