Most relationships start with some sort of physical attraction. Fortunately there are many things that stimulate that attraction. However for long term relationships need to possess much deeper qualities for sustainability. The cause of breakdown in relationships nowadays is partly due to the age that people live and the amount of free time they have compared with the past.
1 . Pheromones
It surprises some people that smell plays a large part in initial attraction and subsequent compatibility. Biology attempts to select a partner who has a very different immune system that is subconsciously picked up by smell. This is primarily intended for procreation of healthy offspring but probably works in a similar way for same sex relationships.
To sustain a relationship you need to have common interests for participation and discussion . People like people who enjoy similar activities and this alone can extend a connection for sixty years plus.
Just as nature searches for different immune response for thriving relationships so it also requires the partners to excel in areas their mates lacks. Differences make life more interesting , helps relationships thrive and cope with change.
4 Acceptance of change
It has been said that many women desire to change their men and many men think women will never change. Good long term relationships refute both. We cant change others but we do change ourselves. Working at a relationship is an acceptance of both and adapting to suit changing circumstances.
I believe humour is natures tool to help us cope with stress I have never met anyone who does not have a sense of humour. However if partners make each other laugh regularly it is a sign that the relationship will last. Sexual attraction and long term relationships will stimulate very different neurotransmitters in the brain so the balance between dopamine the sexual excitement and Serotonin the calm / humorous transmitters can help the relationship to last.
A persons values often show up in little things. Values that are shared in religion ,philosophy or simply a shared profession will do much to glue the relationship together long term. If partners have very different values then the connection will be fraught with arguments and can have the affect of the couple drifting apart.
In the best relationships problems will be deceased early before they build resentments. The ideal method is to put time aside every day to discuss issues. Partners should always be honest but avoid aggression and an accusatory approach.
Erotic love is immediate fast and over whelming. Relationships that start as a friendship can turn into love and are more sustainable. If friendship is not there when the connection is lost people who fall out of love will often separate.
Long term commitment is often but not always related to children There are few things that partners have more in common than natural offspring. Sexual commitment also is usually a sign of long term commitment even if the partners are no longer having sexual relations. Affairs are a symbol of a breakdown in commitment or abuse within the relationship and will be the cause of many breakups even after many years. Commitment is a sign of a desire to remain with one person throughout life and is often expressed through marriage.
People have very different ideas to what gives life meaning. Some couples will not have children as an option so they build their relationship around life goals. Both partners will plan to find fulfilment together and how they can express their love within society as a whole.