Travels frequently to big cities or Asia
Some husbands will spend a great deal of money traveling far from home to hide their deplorable same-sex actions. Big cities offer indulgence of every kind. From gay bars and clubs to prostitutes and sex bathhouses, a man seeking encounters can find them easily if he’s so inclined. Is there ever really a good excuse for a husband to visit Thailand or San Francisco without his wife?
Gym membership but no interest in sports
Gay men use the gym as a place to socialize and to have secret liaisons in the bathrooms. They like to work out their bodies without the competition of sports play. Afterward, they use the showers and steam rooms to engage in sexual activity beyond the prying eyes of women. If your man returns from the gym too exhausted to talk or have sex, that is a worrisome sign.
http://christwire.org/2010/08/is-my-husband-gay/