Extended breast feeding is basically nursing beyond one year.
My daughter is 2.5, still breastfeeds, and her mother is still coming at me like a cat in heat; AND she's also 8 months pregnant.
Unless you're fucking your wife while she's breastfeeding and the kids head is in the way of you groping her tits, having sex and breastfeeding are two entirely separate entities that have no bearing on each other. Unless of course you're a weak bitch like the author who loses his appetite because of something that's occurring naturally.
I love that my wife breastfeeds. The positives are 100x. Decreased risk of breast cancer, diabetes, ovarian cancer and depression, more often than not keeps the mother slim, bigger tits, increased immune system for the child (she's only been sick 2-3 times whereas our friends with formula fed kids have been sick 5 times more), save money, the list goes on..
Author needs to man up.