is it ok not to get married??

my boyfriend and i have been together for 3 yrs. He keeps bringing it up about us getting married and i always tell him “no it’s okay.. “ or “maybe later” but when really i don’t want to get married at all. i don’t believe in it because most of my family has gotten divorces and that got to my head and if god forbid something happens i dont want to be in that mental situation where we have to get a divorce and deal with all that. . But is there a way I can just have my boyfriends last name ? i just want his last name and that’s it. I feel alittle bad because i think my boyfriend does want to get married in his head but i just don’t . 😕but i love him so much