Is your man checking out other men? PROBABLY!!!!
Does it mean that he will follow thru on it? No.
Most people have a blend of same-sex and opposite sex attractions.
But, I do think that as the prohibitions toward those type of feelings come tumbling down this century, that more and more and more men will come out as Bisexual. Why? Because men like a lot of sex, and so two men can have more sex than heterosexual encounters deliver. Simply because they are always in the mood. I know a lot of F2M's that identify with being gay for that reason alone. Lots of sex. More convenience. Less head games.