Ok so basically some quest like get locked if you do it in a wrong order i feel like.

Example 
The Samantha Quest line. I've been going to beach and her house everyday and i can't have sex with her.

I feel like there should be a quest line or quest lock where you can't do other quest until you complete other requirement 
or make an new game+ where were able to reset a quest line or change a choice made in quest 

I will prob wait for 1.8 and just restart my save 

Hello there,

The lock already exists. Example: Ken's quest won't happen until after you have done Sam and Anna has been done raw at the studio. Sam's quest is not dependent on any other, except her own if you decline her.

Have you spoken with her when she is at her Livingroom, are you able to take pictures of her topless at the beach and at home of her ass. If you moved quick through dialog its well possible you declined her.