I took several years of marriage before my wife would let me do that. I LOVED it the first time and after she realized what an intense orgasm it gave her she loves it too!! She has a harder time giving because of her TMJ, but she will give me oral mostly as foreplay. Many people think it is disgusting because they think the area is dirty. There is less bacteria there on both sexes than in the mouth (that is in the absence of any STD's). Urine is actually sterile. So if both of you have just taken a bath or shower there is nothing there that can make you sick or that will harm you.
Like I said, I LOVE bring her to orgasm that way. I love the feeling of her moving against my tongue, I love hearing her moan in pleasure, I love feeling her orgasm, and I love bring her so much pleasure.
The marriage bed must be a place of mutuality—the husband seeking to satisfy his wife, the wife seeking to satisfy her husband. Marriage is not a place to "stand up for your rights." Marriage is a decision to serve the other, whether in bed or out. -- 1 Corinthians 7 (The Message)