Be spacious. Open to listen and feel the other without prejudice.
Be trustworthy. Steadiness and integrity lead to energetic opening in the other as the blocks in relating dissolve away with deepening trust over time.
Having a similar outlook on life is the central key for long-term sustainability in any love relationship.
Good sexual chemistry is fundamental to a vibrant intimate relationship.
What does everybody want deep in their hearts? Love.
Without good communication both verbally and non-verbally, then the love relationship is not sustainable and cannot grow.