Most important...

What is the most important element in any relationship- does not have to be significant other- any relationship....

🙂

Communication!

No. 1 Love
No. 2 Communication & honesty - You must be friends to have a relationship
No. 3 Goals. If you both want the same things in life it helps allot
No. 4 Mutual respect & understanding of your partners needs & wants
No. 5 Attraction helps
No. 6 Humour - you need to both be able to laugh in your relationship

I forgot!! One of the most important things - a virtue which I lack - patience

communication and understanding.