Is there a secret???

So today I'm having breakfast this morning at my local cafe reading a book called How to Talk to Anyone...then this totally random though pops into my head..."What is the secret to a true long term relationship??"  I though I knew many things about relationships but coming out the end of this most recent relationship I realise I know very little about how to make a relationship last beyond that first few months of total infatuation and engagement with each other. 

After the initial few weeks/months...how do you keep that spark alive?  One train of thought is well...have an open relationship.  I can't express how much this goes against my values but at the same time the thought did cross my mind in this most recent experience.

I think though communication overrides absolutely everything and well...I think I failed miserably at that...although not for want of trying.  But communication and people are my downfall at times if not always.  This is something that I'm working on regularly.


But it still doesn't answer my question about is there a secret?  I see many people in love and happy in there relationship after one year, five years, ten year and even sixty or seventy years!!  It makes me wander is there a secret or is it the chemistry, meeting the exact right person or...who knows.

I'm not expecting an answer but I just want to put it out there to the universe!!