Several years ago, one of my dearest friends called and told me that she had started dating a guy. It was obvious withing minutes that she was head over heels. I happily listened as she talked about him and his personality and my dismissive thoughts were quickly replaced with thinking that this was probably going to "work out."
I initially dismissed the relationship because they were both very young. He hadn't served his mission. I wanted her to graduate, have the chance to explore the world, and do crazy and fun things.
The more I listened, the more I realized how mature their relationship was. The clincher was when she told me of how he had offended or hurt her by an action or something he said, and instead of bottling it up like I would have thought she would do, she confronted him. And instead of getting defensive or dismissing her, he validated her feelings, apologized, and promised to never do it again.
I was so stunned. These were 18-year old kids! I knew people ten years older that wouldn't have handled the situation as well as they did. I still don't know if I would have - being on either end. But that's when I knew. I knew they were going to get married. And I knew they were going to make it. He served his mission, and she waited. He took a job at home, and she waited. And when they got married, it was one of the best weddings I'd ever been to. I'm sure it's been an adjustment, and yet, they are happy.
I think it's important to be in a relationship where you feel safe to bring up your frustrations, and talk about what hurts you and makes you feel bad. If you don't feel safe doing that - if you feel like the person is going to get upset, or leave, then you need to reevaluate. I think it's a good indication in dating, especially, that if you can't bring to attention something that the other person is doing is making you crazy or hurting your feelings, that that person is not the one for you. It's never easy to confront someone on their alleged poor behavior, but... you have to be able to do it. And on the other hand, you need to allow for others to come to you and voice concerns and unhappiness at what you do. We are all imperfect, and we all make mistakes, it's so much better in the long run to be able to look at something, apologize, and try to never do it again.
I am still blown away that I learned that from someone so young, and yet, it's one of the many lessons I've picked up as I've observed successful couples interact with each other.