When you hear your friends complaining about their relationships, you do not relate. So, if your friend keeps telling you that he and his girlfriend have a lot of problems and talking about her flaws, you feel like this is a distant feeling for you because you are so happy in your own relationship. The only advice for you would be to keep this feeling to yourself, and not be like “I understand you, but my girlfriend and I are completely happy”. Your friends might be frustrated and find you selfish if you decide to drop your happiness on them at the particularly bad timing.
She supports you all the time. All the strong relationships were always based on mutual support and understanding. If you found a woman who believes in you and thinks that you can do anything and supports you even through your darkest times, then you are really lucky to have her. And you should also have confidence and faith in her when she doubts herself.
You make future plans together. For example, you can purchase the concert tickets for next year, or book a holiday, and you are not worried that she will break up with you by this time. This is called complete trust in the person, and if you both have trust in each other, it is a brilliant sign. This means that you are a giant part of each other’s lives and that you are certain that your future is together.