It can be hard to tell if your man is gay. But, there are some clear signs that you should watch for. Some of these signs are physical and some are behavioral. The best way to know if your man is gay is to ask him! But, if you are not ready to ask him then you can try observing his behavior.
Do his eyes wander when he is around men? Does he seem to notice more men around him than other people? If so, he may be interested in other men. He may also be more comfortable using the men's bathroom rather than the women's toilet. This can be a sign that he is open to homosexual relationships.
Does he hold hands or touch other men? He may be very touchy feely around his friends or even co-workers. If he tends to hug his male friends or he is always grabbing other men's arms then this could be a hint that he is gay.
If he has talked about having a sexual encounter with another man in the past, this is a big clue that he is gay. This can be a difficult thing to admit so it is important to have a discussion with him about his past experiences. He may not be ready to talk about it or he may be lying but, only you can decide if his honesty is worth the risk of losing your relationship.