Interesting point about the mother guilt.
As any 4yo can tell you, play is usually a lot more rewarding for its own sake when it's done in a collaborative setting. In that context, mothers who engage in that sort of play with their children and partners can justify their own pleasure (an alien concept) with the assurance that they're being really great parents/partners in the moment.
I continue to prioritize play each day with my DD12. Apart from the direct benefits of play itself (of which there are many), it strengthens the bond and provides tons of unexpected teachable moments.
