Confused

This is terrible but I have been with my boyfriend for over a year and a half. He's my first for everything except kiss. Honestly I can see myself spending the rest of my life with him and I love him but I wanna know what it's like with someone else. Me and my boyfriend never fight and I know he won't cheat on me and I won't cheat on him so there is no real reason why we would ever break up but I really wanna know what it's like to have sex with another guy. Is this bad?