For me to have a successful marriage you need:
Love
Respect
Honesty
Communicating
If you have all ingredients listed here this is enought.
Don't think performance for sex is a priority because if you communicate with you partner you don't need to have the top partner, because you can make learn the person what you want and also you can learn togheter what you never expected from yourself.
Everything is a question of respect and communication and honesty, but you will not do this if you don't love the person. This is why I have listed them togheter.
Don't think we need passion, I think a lot of people is wrong on what passion really is. Passion is provocate by the insecurity to loose the person you share. Insecuritry can be caused by multiples events: lies, if you are not respected, when you are sad, when you think your partner loves someone else, when you think your partner will leave you, when you think your partner don't talk to you enough.
Love is supposed to gives you the feeling that you are so confortable that you don't want to move, like when you are sleeping in a so confortable position that you don't want to move a finger.
Respecting, communicating with you partner this is what is really important. People have to learn that we can not read in the mind of someone else, and they need to know by telling them, this is the most effitien way to do it. Sure we can guess, but a guess is a guess, and not always what it's supposed to be really. Being honest with your partner is not easy because you need to be honest with yourself first, that means you have to know yourself alot.
Sorry if my english is poor I'm too lazy to check what I wrote hehehehe
Please Jafo forgive me