My sister has 3 kids from using the pullout method. So, yeah it works until it doesn't. Don't do it unless you have a birth control method in place. I know your primal caveman brain wants to do it because it'll feel good, but seriously don't. Unfortunately there are no reversible methods available for men other than condoms, as you're too young to get a vasectomy. She could look into the non-hormonal copper IUD, but they can be expensive in some countries and they can make periods worse.
My sister has 3 kids from using the pullout method. So, yeah it works until it doesn't. Don't do it unless you have a birth control method in place. I know your primal caveman brain wants to do it because it'll feel good, but seriously don't. Unfortunately there are no reversible methods available for men other than condoms, as you're too young to get a vasectomy. She could look into the non-hormonal copper IUD, but they can be expensive in some countries and they can make periods worse.