Why would you want to change the girl's affection for herself? Oh I see, you forgot to search this thread and find the earlier replies or the guide where the answer clearly states that you when using the console codes you have to specify to whom you want the affection, favor, love, etc. directed.
I'll save you the time. Other than lust, the code for affection, love, etc. must include the specific person you want that particular feeling directed to.
The code is: "girls name".rsm[0].affection = XXX
Same code for the other feelings, just replace 'affection' with love, favor, whatever. The [0] indicates the player or MC. Just as an FYI, it is best to check the highest level for each girl. If her cap is at let's say 50, inserting 100 runs the slim chance of causing a fatal error and 'borking' the game.