The fulfillment you get from a relationship will ultimately be determined by the style of relationship you lead and create with your partner.
Level 1 - The Independent Relationship - Each partner is only concerned about getting his/ her own needs met. This relationship is all about taking. These types of relationships are short term, due to their nature they cannot last.
Level 2 - The Bartering Relationship - Each partner barters for his or her needs. This can be defined as "I'll give you what you want, if you give me what I want". It is horse trading. These relationships can last. However, they cannot bring about lasting intimacy. Typically the emotional side of communication becomes too limited, because each partner feels that there are only certain situations where they are free to communicate their real needs. They are limited to do this only when they give and the other gives.
Level 3 - The Unconditional Relationship - Each partner puts the other partners' needs first. This is an unconditional relationship, where caring for the other (or loving, or giving) is unconditional. This type of relationship can endure the inevitable bumps that each partner goes through, by fostering a stronger trust bond between the partners.
If you are interested in developing longer lasting and fulfilling relationships, you should pursue a level 3 type relationship. It takes more courage and strength to pursue this type of relationship, but the long term rewards are much greater.