sexual relations

a woman may have her sexual desires interfered by her external situation. She may want to be intimate with her partner but something (stress, uncertainty, distraction) is preventing her from being present in the moment, and thus prevents orgasm, complete letting go, or feeling like she is a part of the connection. How can she heal this?
I don't know where to start looking for healing in this. To look inward in this instance is confusing. I am not sure where to turn. Is it mental? Physical? Spiritual? Do men have the same experience? Though I try to discuss this with my partner, he states he does not understand because he can't find an answer or "fix". I question if it is truly a problem, since I know in my heart that it is temporary. How can I help him understand this? How can I help him through this so he does not feel rejected or pull back? His solution is to quit being intimate for a while. My heart feels broken when this is the case. I feel we need to work together, not apart on this issue, but perhaps he is right. Since it is my head that is getting in the way, I recognize that I need to do my work in this area.
How can I start this work? Where do I look first? Can I affect change in some area of my life where I am not? Is it a reflection of my inability to be present elsewhere in my life? Is there something between us that is missing? I find him incredibly attractive. Our most recent sexual experience was the best yet, so I don't think that our sex life is troubled. However, apparently it is...
Ladies, can you give me some clues, ideas, or suggestions?