This is not an obvious achievement. You have to fulfill 2 conditions:
1 - John can not die before "Heavy Burden" chapter.
2 - I am not sure but I think you have to choose "Please Hurry!" as Angela, then they both fight aganist 2 monsters. You have to do QTE (QTE = It's this minigame when you press B,X,A and Y to survive) as well. After you reach the house and John will block the doors you have 2 choices, you have to choose "Leave me and go!". After this achievement should pop.
I am sorry if something was not wrote correctly but I am not native english speaker but I tried my best to describe it easy.
If you have a question you can add me GT - BajerKR and I will try help :)