Relationship definitely got its ups and downs but I think applying the following principles will help in ur affairs
They accepted each other for who they were and learnt to be thankful for each other and God for the chance they had to be together. They didn't take each other for granted. Appreciation could also show itself in little gestures of love like running errands for each other, getting gifts, saying 'thank you'.
I believe the lines of communication should always be open even when you are mad at each other. It does no good to keep malice or ignore each other. Instead, being able to openly state your opinions and grievances is a way to keep your relationship alive.
This is a big one but no relationship can stand the test of time without it. This is blind faith in your partner and ability to cast aside insecurity.
Sacrifice is an integral part of love. You won't always get your way but couples that remain in love irrespective of time have learnt to put each other first.
This is the ability to bare oneself to someone else even if it means being vulnerable. A relationship devoid of lies and pretense always lasts.
Watch this space for the continuation. You'll be glad you did.