If you get excited about seeing him romantically, sexually then there are chances that you are gay. When you don't find your hormones getting excited when you spot a beautiful woman, then you need to check if you get attracted at very high levels when you see a man. But if you find yourself checking out other women when other men when you are with your girl, then do think it over again.
If you are a man and you have a girlfriend, and you check out other women while you are with her, then it's not a big deal. When rejection could entice you to get together with another man physically, then there are chances of you being gay. If ever a girl has rejected you in your life and you had felt better while connecting with a man more than just emotional space, then you need to ponder about your orientation. However, it is recommended to consult a psychologist or a renowned psychiatrist to elaborate on your past experiences and try to fortify your orientation.
If ever in your life, you had cheated a girl for another man, and then it surely indicates that you have some extreme level of attraction towards the man more than what you have for the girl.
