Before going into full "agree to disagree" mode with
Darkhound1, you might consider experimenting with adjusting Natasha's 'Affection', 'Love', and 'Lust' values via the Companion Mod prior to sending her home and bringing her back. There may be other nuances to consider as well before declaring conclusively that you have tried
everything and that the game's developer is wrong. If the developer can't replicate the problem you are experiencing, it's likely that there is some combination of values, circumstances, and prerequisite achievements in-game that will result in the desired outcome for you. I'm not trying to be confrontational, I'm just trying to offer what are hopefully some helpful suggestions.