Getting Penelope's final scene is the hardest in the game since you have to have a relationship on Lauren's birthday in CK1, in CK2, personally I haven't been able to complete the party on CK2
And the "girlfriend" part has not been created yet, if you have played CK2 the latest version you will have seen that new "paths" will now be opened with girls that you could not have a relationship with one if you were with "another".
This game is listed as harem, but in my opinion do not expect to catch them all ,this is not Pokemon