David Richo writes,

Behind every complaint in a relationship is a wish and heart desire for attention, allowance, acceptance, affirmation, or affection.
Love is experienced differently by each of us, but for most of us we feel loved when we receive attention, acceptance, appreciation, affection, and are allowed the freedom to live in accord with our own deepest needs and wishes. We need these to develop self esteem and a healthy ego.

Richo refers to these needs as the "five A's" in his book "How to be an Adult in Relationships" which is a book I recommend for a further exploration of how each of the five A's may manifest themselves in a relationships. Of course, simply identifying what may need to be done to improve our relationships is only one aspect of the relationship dance. If we aren't able or willing to do what we clearly know needs to be done than we may need to further explore why and what obstacles may be preventing us from providing our partners with the attention, acceptance, appreciation, and affection they need and deserve.