I feel the same way. For me love is pain also. But I believe it is because of my patterns of the past in choosing men who are not available or appropriate for me. I think you have a pattern of loving men who are married?
I am reading "Calling In the One" it has lessons to go over each day and it focuses more on yourself and helping you uncover the patterns that make love something that is painful. I have heard that this book has worked for many people. I am also doing Recovery of Your Inner Child" I am finding it helpful to release beliefs about not being loveable or deserving of love.
Love shouldn't be painful.
I attract men who are more and more suitable for me To me this is a sign that you are making better choices and I'm sure the right one will come along soon.