Stick to your commitment (even if you are just dating) .. and forsake all others...unless you have discussed it with him about seeing other people. Do not start out your young adulthood by getting comfortable with lying and deception.
If you love the boy then you love him. But if you're still in love with him and like another boy, you might not really like him. you might think he is cute or sweet. If you start to feel like you are developing a crush on him then talk to him. Get to know him more. Ask yourself: which one loves me right now and which one do I live more? Most likely it will be your boyfriend