fantasizing about being with other guys

so i have a boyfriend of 2 years, everything is good, sex is good blah blah... well i go to college , in this class i have there's a guy that has been talking to me flirting in class only... he's black and cute lol and i feel like ummmm horny around him 😒 ugh dumb and weird i know.. is it normal to feel like that?? just fantasused by other guys and sex? 😐not that i wanna have sex with him because i respect my relationship and won't do a cruel thing... but why am i feeling like this ?? i just wanna quit college because of it... It's not just the black guy it's other guys ... But i don't even talk to them back i just say one word😫😫help!!! my uterus needs to be stabbed