After having children, women tend to view themselves as primarily a parent and less as a wife or intimate partner.
Men still though view themselves as a lover or partner.
Maintaining intimacy must be maintained and it takes work.
A partner takes precedence over the children. The greatest gift that a parent can give a child is their great marriage.
Maintaining physical intimacy is a conscious and intentional choice. It rarely "just happens", particularly once children arrive.
Children feel safe in a thriving marriage and to see non-sexual affection is great for them.