When you say that your wife has "lost sensitivity," what do you mean, that sex is not giving her orgasms? If so, is the problem that she doesn't want to have sex as much and this is negatively impacting your sex life with her? Or are you saying that you just want her to have pleasure?
If she is content to have sex with you whether or not it is as exciting for her as it was before she had six kids, stop with the suggestions and the props and simply have sex. If you "helpfully" suggest things to her like ben wa balls and Viveve and saying she should "keep trying," you'll just make her feel like you think she is deficient. I am serious about the shutting up with the comments. Taking care of six kids is exhausting. On top of that, let's say you were she and she was you, and she came at you with penis enlargers and creams and pills and said "keep trying"? You'd feel like she was saying you were a loser.
If the problem is that she has lost interest in sex entirely, then you guys have some considering to do. Is she willing to do things to please you even if they don't mean a lot to her except that she wants you to be satisfied? Try hand jobs and other ways that don't involve the vagina and excessive effort. (Would you be willing to accept that substitution?)
If you think the problem is that your wife is simply run off her feet by the challenges of taking care of so many kids, and the last thing she needs or wants is another obligation for which she doesn't have time or the impulse, you two might have to talk with a counselor to decide where you two can make some accomodations. In her heart every wife (even one totally emotionally drained by her life) knows she should have sex with her husband if she wants to keep him happy. She knows this even if sex has lost its meaning for her, or has been pushed to the way back of the list of obligations. So decide if the problem is emotional and/or simply exhaustion, and decide what could help. I once suggested to a guy who wanted more sex with his wife that he should come home every day for a week, take care of the kids, clean the kitchen, start dinner, and make sure the kids' rooms were clean, their clothes were ready for school the next day (and their homework), and the laundry was going. He said "I don't want sex THAT much," which made me laugh. If my husband would even act like he knows such things exist, and was sympathetic to and with me on the need to make them happen, I'd be a much hornier wife.
Good luck! I don't think it's really a matter of pills and creams and devices.
Hello! Lots of long term couples have to work through sexual situations as the relationship goes along in years. Six kids is a lot of kiddos and I do want to point out that with just two, I was (am) frequently tired and not always feeling sexy. Life does change in that way. We also can have changes in hormones that will affect things like lubrication.
Since you say she had six births, I am going to just cut to the chase. Is the loss of sensitivity yours due to your perception she has stretched out? I looked up viveve and the concept of the ben wa balls and am wondering if that is what you meant. Clarify that and remember, we're anonymous here. So, we're just here to help and you can talk openly.
Some women do lose elasticity of the vagina. We're supposed to do kegal exercises to help with this. Heck, men should do them too and strengthen their pelvic floor as well and you could say let's both do it or something.
I understand it is sensitive subject. The most important thing for her to really come away with is that you love her and desire her. Clarify the issue and we'll go from there.
I just wanted to say thank you for the responses I have had to my question. I am glad I asked because I feel like I really would have gone the wrong direction on this one. I appreciate the various point of view.