This has been a brainteaser since ages. Has anyone come upon a balanced solution that is universal to everyone? Not really! Mutual trust, respect and imparting individual spaces have been the paroles of experts and experimenters.

I would start with listing of some important aspects that I've come across. These indicators in no particular order would surely be helpful for a relationship.

Friendship would be the foundation of a romantic relationship or for that matter any relationship. Imagine a relation, the one with - partner, mother, father, brother, sister, friend etc without the crucial component called friendship. It would be a relation without a soul and hence lifeless and short-lived.

Commitment is another element that will help the relation sustain through tough times with sincere efforts put up by each of them.

Respect and Trust is the factor that stabilizes a relationship.  These qualities overpower the inevitable aspects of a relation – Control and Jealousy. The latter ones make the individuals feel trapped, while the former makes them free with the relationship thriving.

Love Yourself
Accept your imperfections, know your limits and indulge yourself in things you are passionate about other than the partner ;). Only then can you appreciate the beauty of life and love.

Be Supportive
Build a strong emotional support system, and comfort one another in troubled times.

Acknowledge Differences
Resolve disputes by expressing and analyzing it; this will help cut across the awkward situation with ease. Face it to overcome it. Avoiding conflicts with effort would complicate the relationship, communicating will help strengthen the above stated elements.

Phew! An imbalance in the elements cited can be disastrous in a relationship. I may have missed out some more attributes. Lets complete it with your inputs.

wow superb collection dear and nice thoughts also

hey wanna add a thing

caring other: care the people who cares you and the one who does not care also..... it will increase your personality as well as your value in the society.....

good listener: a good listener is the bet person in the world bcoz he/she has the maximum power of tolerate and they are very stable..... have a good patience that will keep you cool and happy........ health will also affect by this

how to make a long relationship? well established trust each other. never ruins that cause if trust lost your relationship is like a house without a foundation thats easily to collapse!