Biggest decision of my life, i need some advice :/?

im 18 years old and have been with my boyfriend for three years, hes 19. yesterday his work offered him work in australia, half way round the world, for a year to two years. he wants to go because he sees it as he might not get the chance in the future when he's settled down and has a family and i agree. the only thing is he's asked me to go with him, i know he will go whether i go or not and i don't want to hold him back but i don't know if i can just drop everything and go, but at the same time i don't want to lose him. i'm stuck and don't know what to do :/ please help.