Dr. Joseph Nicolosi and his colleagues at National Association for the Research and Therapy of Homosexuality (
www.narth.com) have some excellent and helpful articles on their web site. I think you can get some good answers there. Dr. Nicolosi has worked with hundreds of men with same-sex attraction. He sees same-sex attraction as a drive to repair a man’s damaged sense of masculinity. This emotional need sometimes seems to the man to be a physical need, and so is sometimes expressed physically. When the man’s emotional needs are met, the physical attraction toward men is often lessened, and sometimes he begins to experience a natural desire for women.
In the case of women, same-sex attraction is more often felt as an emotional need rather than expressed physically. According to this site, the origin of same-sex attraction in women is more complex than for men. I highly recommend this Catholic-friendly web site.
P.S. This site does not insist therapy is necessary. It does insist, however, that it should be available to those who desire it.