May I ask how old your wife is? What your discribing isn't uncommon at all. I hope your realize that. It tends to be a time in a women's life when being a mother is the most important thing to her. She may not act it, she may pretend it's not true, but she's hardwired to put the kids first.
There comes a time in a women's life when that completely changes. It's like a switch goes off in her head that tells her sex is now really really important. The problem is that typically the H's switch was turned off for good long ago.
One of God's biggest mistakes...A male peaks at what 20, while the female peaks at 40!
Gigi
"It's not what happens to you, it's what you make of it." Zig Ziglar