Unfortunately, even after replaying the 'Date?' and 'Honesty' chapter, I still got the same ending. I'm sure I have over 50 points with Lock too because I'm able to get the R18 scene. Is there some other requirement for them to become boyfriends or is my game broken? ;-;
did you replay Final call as well? Im not sure what went wrong. Altho opening the sex scene isn't a clear indicate of 50 points. A clear indicate is Locks reaction to Keyes being what he is in the Asylum. If he freaked out he is below 50, if not it is above. If the ending is still stuck in Darkness, try this https://steamcommunity.com/app/1343220/discussions/0/4336358006696848283/
sorry if it still doesn't help :')