The infatuation stage is not women trying to seduce men into marriage -- it is men being so overwhelmed that they drop everything to be with their women 24/7, hang on their every word, do things like constant attention at home and more willing to give massage early in the evening. It is hormones of both men and women caused by the newness of it all and kept at a high level by all the attention and special treatment.
Interest dies off after 2 to 4 years unless pre-sex activities which meeting a women's emotional needs are done. It can also die off if a woman is too stressed out by child rearing all day long and has a personal need for more adult interaction in life than she is getting on a daily basis.
But, you can alter your lifestyle to keep meeting each other's emotional needs after marriage...Sometimes you need help to find out what each other's needs really are, since people tend to project their own personal preferences onto others by assumption.
Little things, flowers every week or two, foot massages after work, doing the dishes for her daily, putting the kids to bed and helping with homework daily, ignoring her pretending that she doesn't need to go out on the weekend to spend money on a couple's date and just doing it anyway because you know you need to make the time to keep the foundation strong. All of these make sex more often.
The one thing that is nearly insurmountable is the once a month cycle. As long as I live I will always count the days from the start of PMS until the end of a period (often 10 or 11 days). Sex during PMS is possible, but not probable. Sex during a period is not likely after a few years of marriage.
In my first life the XW moved into her own bedroom 18 years into the relationship. Sex ended for the next 2 years, followed by Divorce. In my second life, 7 years ongoing, sex is about the same ever since the baby 6 years ago. Twice a week mostly, sometimes 3 times, rarely once a week. Don't make sex an issue, if I need it, I make my behaviors more attractive to her ahead of time. Don't resent that aspect, it is just how women are wired.