The thought of your relationship makes you smile: When you think of both of you together you don't experience anxiety or stress. All is quite well with you both. :)
You make each other smile: Keeping each other happy and satisfied is high priority. After all a happy relationship is what you both want.
You deal with arguments positively: You have them yes, but you've learnt to deal with them and move on. Instead of keeping scores, you forgive and forget.
You acknowledge problems: You want an ideal, happy relationship but you are willing to acknowledge the problems too. If there are certain things that are causing harm, you address them rather than shoving them under the carpet and pretending to be happy.
You know each other's families: You no longer have to hide the relationship from your parents. Since you both are secure in your relationship you are comfortable enough to introduce each other to your parents. Read more on idiva.