@The Pentacle Queen,
I think the answer might be slightly different from male & female perspectives.
I have noticed that in almost every instance where a guy complains of not getting sex anymore...they also aren't putting the effort and/or time and/or thoughtfulness into the relationship...while those that don't complain constantly seem to put these things in to their relationship.
Basically I think that:
- you put effort into the things that are important to you. And your partner knows how important they are to you (in comparison to everything else) by how much effort you put into her.
- replace the word 'effort' with either time, or thoughtfulness, and the sentence still remains true.
Other than that, there is also how you handle conflict. Couples who fight fair generally last longer together.
I think maybe (though I have no evidence for this) the small things become more irritating as the above things get worse.