I understand that there are different types of relationships, and I am not claiming to be an expert of them.
Although, I feel compelled to say a few words here on this subject, in regards to intimate relationships.
My focus for an intimate partner is a male, but I remain open that others might find their partners to be of the same sex.
  Regardless of this I still believe the thoughts expressed here can be applied to all intimate relationships.

Within a relationship, Respect and Trust are vital ingredients for a healthy, successful joining of two people.
  There are many couples who have disregarded each others needs and  desires.
Rather than openly communicate they hide their needs and build up anger, frustration and resentment.

To openly respect the other person you are mated with allows them the freedom to be themselves.
  They find no need to conform to a fantasy of what you expect them to be.
   Continuous communication, and revaluation of your relationship will enable each of you to focus not on hurt feelings,
 but that of your mutual enjoyment.
    By openly sharing all interests to your mate, you are trusting them beyond what you would give to any other person.

  Let your mate see you completely without fear of condemnation.
  I despair for couples I see who have their own hidden agendas, whether malicious or not.
  Men and Women hiding their needs and fantasies from each other can only lead to misunderstandings.
How can you truly love someone you do not know, or who does not trust you enough to allow   you in their heart. 
Otherwise you are only in love with an illusion.
Speaking from a female perspective, I find many woman who are willing to share in their mates fantasies,
 (i.e. Erotic art or movies etc..).
  Concurrently their mates have no desire to share these things with them and continue to pursue these needs in private.
  This only creates walls between them, and hinders further intimacy.  Believe me when I say that sharing such needs openly does not hinder your relationship, instead it nourishes your connection . 

Please do not take what I am saying the wrong way.
I do not suggest  playing with fire, such as open relationships.
  I am strictly speaking about a couple here, who can communicate and trust enough to be themselves.
   It is important to maintain your comfort level.
  Participating in activities that could be emotionally harmful,
 just to please your mate, 
is bound to be destructive to your relationship in the long run.
    Continually be open to your mate about your needs,
 and show your willingness to be open to theirs.

  If the other partner of your intimate relationship knows how strongly you feel about something they should try to meet you half way,
 so both of you can be satisfied.
Mutual satisfaction is definitely an achievable goal.
Not that it comes easily,
 but neither does it take excessive work. 
The work seems to arise when  intimacy is lost, and needs renewing.  Keeping the electricity alive in your relationship should not be  happening only physically,
 do not allow your self to only feel sparks when making love.
  Mentally and emotionally stimulate each other.
  Build on these moments and develop intense passion for each other.

I will attest to the completeness this allows in a relationship.
  I feel cheated if not allowed to relate to my mate mentally, emotionally and physically.
  I have been there before and found it not only unsatisfying but downright painful.

  Each element of the relationship adds more enjoyment to the others.  Sexual intensity increases with such complete intimacy, 
it can go beyond the physical act.
  Allow each other to be sexual creatures,
 try not to fit your partner into a pre-conceived  mold of what is sexually appropriate to you. 
 Again, be open and honest with each other.
  Explore you mutual needs and desires, and communicate them to each other. 

Most importantly, respect the trust the other person gives you,
 do not abuse it.
Mutually committing yourself to a relationship places each of you in a vulnerable position.
  Guard the love the other person trustingly gives to you.
To use it against them  would be one of the most  hurtful things you could do.
  I cannot believe how many people disregard the feelings of the one person they claim to share their love with.
  It goes beyond legal vows.
You commit, not to the state or church,
 but to each others heart and soul.  
Be true to your  mate  in all regards.