Edit: Before people try to fight me about this, I don't think that women should dead bedroom their husbands. I think that couples should be having regular sex and meeting each other's needs to the best of their abilities. This is my attempt at explaining a phenomenon, not excusing it.

/disclaimer

So I run across this pretty often in PPD. People (usually men) will talk about women hiding their "true nature" until marriage. They say that women put up a good false face until they can snare the commitment they want. Here's a real comment pulled from PPD to demonstrate what I'm talking about:

A lot of the time it's women using hot monkey sex to reel him in and secure the ring and the date; then cutting him off immediately after that.

While I'm sure this happens sometimes, I think it's probably rare. I believe that men are reading intention and premeditation where there is none. An alternate explanation is that the women lose attraction to their husband over time.

A platitude I see repeated around reddit a lot is the idea that "people don't change." In reality, people change a lot over the course of a LTR or marriage, just not necessarily in predictable or planned ways.

Off the top of my head, common life changes that affect many married couples include: career change, loss of job, death of family member, birth of children, returning to school, moving long distance, military deployment, illness, progressing age, and weight gain. These drastic changes in circumstance can prompt personal change, which will have an affect on the attraction/sex within a relationship.

It's unreasonable to think that people will stay the same over years or even decades, considering the huge variety of events that can affect couples within that time.

TL;DR: I don't think she tricked you; I think she (and you) changed.