Is it better to lower love or respect or keep one or the other high for the cuckold path? I don't want to make all the wrong choices and miss content. Logically it could go either way and without a walkthrough I'm a bit lost.
Feel free to play the LOVE angle how you want to be seen by your wife. It is pretty common for a wife to love her husband and still cuckold him. Many such marriages last forever. If you want to be unpleasant however, you can still do this - she might not love you so much (or at all) - but this might make cuckolding you easier for her. I don't want to force players to act in a way that they feel uncomfortable with - they can play as themselves or as a fantasy self.
However, the RESPECT stat should be reduced. Some women refuse to cuckold their husbands as they respect them too much - they don't want to lose that respect for them. So to help nudge your wife along that path, you need to do this. My view is that although a married couple's love can remain throughout a cuckold lifestyle, every time a husband lets another screw her in front of him, her respect for him diminishes a bit.
Take a look at the
Developer Notes section on Page 1 too.
Don't worry about game killing decisions though. I don't really believe in them for this sort of game - I want you to get to the content you want. There are plenty of occasions in which you can affect your stats.