The dating site could be harmless, just him looking for others with the same interest. Not sure id you mentioned what that was? I have a girl pal-Whom was in the same boat but his preference when he finally got to talking 24 months later 2 years, she found out his male preference was stronger than his female attraction/sexually. Don't go in biased and blind see what signs there are there maybe some warning signs for you. I could say he is damned blessed to have you as many wonderful folks would love I mean LOVE to have a woman of you persona with them. I think he maybe in need of what you cant give him. You may try only to find years and tears of your life slipped through our tiny hour glass called life. You have a RIGHT to be happy too. I'm not giving any advice except please keep your woman's intuition & please look for signs good and bad--Clothes doesn't make the man-Your right--But truthfulness & communication make a relationship-I believe that with ALL my HEART--Blessings.
