Most Helpful Guy
Well I agree with your premise, but disagree that "there's nothing you can do". You're right, a woman can't replicate the first time with a long-term partner... the feelings or excitement. But New Pussy's illiterate. New Pussy can't cook.
People have to learn to appreciate the stability and lack of drama that an established relationship can provide, regardless of how "unsexy" it seems.
And people need to do the best they can to keep the relationship and the sex fresh. When you hear the phrase "relationships are hard work" I think that's what they're referring to.
You can never fully prevent someone else in a relationship form doing something, but you can certainly provide a disincentive.