Its definitely not always the mans fault but we would do well to understand that men don't have the same needs when it comes to maintaining a long term sexual relationship.
Women generally need to feel a sense of emotional security, trust and connection for a long term relationship to thrive, especially in the bedroom. Men would like this too, but they don't necessarily need it to continue a sexual relationship.
Unfortunately in many (perhaps most) relationships women do feel that a disproportionate share of household and childcare duties fall on them, which erodes at those core foundations of a healthy long term relationship.
Is it all on men to work this out? No. But if they want to take an active approach to maintaining the health of their relationship, meeting their partners emotional needs has the highest likelihood is doing that and keeping the bedroom alive.
Women like to be physically intimate when they feel safe, understood and appreciated. Men should ask for the same in their partners even if we're conditioned not to 'need' all of that in the same way.