1. He's always telling you how much better his night out would've been if you were there. It's not like he's constantly pining over you just because you're at work for the day, but he wishes you were around when something exciting happens, and he can't wait to share funny stories with you.
2. You spend all day in bed together. Not every day (because that would make for a terrible, barely functional relationship), but that first day you spend in bed together, just talking and laughing (and sexing) is always a good sign that the relationship is going places.
3. The sex is great. This is key. Sex isn't everything, but good sex means you've got a connection.
4. You can spend a day doing nothing. You don't even have to talk. You can sit in silence reading your own books or just relax outside in a park. Being together is enough.
5. You can always make him laugh, sometimes with just one word. You might not be the funniest people in the world, but you can crack each other up. You have a ton of inside jokes at this point, and you know exactly what to say to make him laugh uncontrollably.
6. You really "got it" when he had a crisis. You understood him when he was stressed out and not at his best, and you stuck through it with him. How you act when the pressure is on says a lot about you.
7. You show interest in the things he likes (and he shows interests in yours). You don't both need to have a deep passion for whitewater rafting to be soul mates. But you do care about the things he loves, precisely because he cares about them. So even if rafting isn't your thing, you tried it because you knew it would make him happy.
8. You can tell he's really comfortable around your family and friends. He doesn't have to be best friends with everyone you know, but he at least feels welcome.
9. He credits you with his big promotion at work. He really feels like you make him a better person, because you encourage him to go for it. You're supportive, but he doesn't feel like you're being pushy, because you really believe in him.
10. He loves that you introduced him to fusion Thai food. And modern art. And Taylor Swift. You open him up to new experiences and take him out of his comfort zone. And he loves what he's learning.
11. He can't keep his hands off you. You two still fool around like it's the first week you met.