Invite her to a date after you have finished every quest with her. You'll have to choose from hug to kiss to vaginal to vaginal+anal and then to extreme. Remember, you can only do one date each day.
Lad i am in the 0.5b version but. i can only do the HUG scene, if I press other options just like you said it says "not good enough relationship " what do you think
Might be a bug. If you have a previous save when you have not invited the brunette nun to a date, start from there and try again. If it still persists the developers will fix this in the next update which will be released around the end of September or early October.
