In many ways, there is little or no diference between gay and straight relationships, especially with regard to their emotional problems. There could be numerous reasons why within a long-standing relationship one partner or both might lose sexual interest in the other. DO you have a continuing sexual interest in others ? Do you continue to be sexually aroused, eg withi masturbation ? In other words, is there a general loss of libido on your side, or is it specifically concerning your partner ? The way to seek a solution would be to see a good local shrink or counsellor for relationship counselling, to seek to understand what may have changed within the relatonship and to see what might be put right