I'm not going to pretend that I know all the answers to those questions but I do know that the way we communicate with each other plays a large role in our chances of living 'happy ever after'.
There is a very effective communication tool developed by Shelly Gable et al (2004) called Active Constructive Responding (ACR). When we learn to respond to our partner (or friends, children, work colleagues) in an active and constructive way, the person you are talking to benefits and your relationship with that person strengthens.
Most of us automatically communicate in a passive/constructive manner. This is neither beneficial, nor especially bad for the relationship. An example of passive/constructive communication would be when your partner is sharing some happy news with you and simply respond with, "that's nice sweetheart, I'm happy for you"......on the surface, not a bad response but on closer inspection, it's not especially engaging, nor encouraging the person to deeply share their positive experience.
More damaging to a relationship is using a passive/destructive response (e.g. what's for dinner? - simply not even acknowledging what has been shared) or an active/destructive response (e.g. they must have been hard up for people if they chose you!).
Real power and connection for relationships comes when we use active/constructive responding, which would look like, "Wow, that's amazing, please tell me exactly where you were when you heard that.....explain the feelings you felt when they told you.......I can easily see how your strengths support that, they must have seen that in you too....." etc. You help your partner to re-live, or savour, the positive emotions they felt and you flesh out, with genuine interest, the things that contributed to the positive event happening.
Gable found that how people respond to good news significantly predicts the quality of the relationship.
My hope is that before relationships drift and assumptions begin being made, that people will honour rich listening and generous questioning, using Active Constructive Responding, to promote the sharing of positive emotions and experiences.
And may my friends who married today live happily ever after!