I think VR is a great thing, and I also think that the concept of using VR to communicate with my waifu is also a great thing. On the surface anyway, the thing that will most likely keep me away from VR of my waifu is her voice. For me to be truly immersed in a VR, I would have her exact voice interacting with me. Maybe voice synthesis programs could improve in the future, but I'll have to wait and see.
I have no idea if VR sex will be immersive enough for me to enjoy it. I would guess that it would be something enjoyable but would it be more enjoyable then just my imagination and my hand? VR kissing is something I could easily get into though.
Waifu robots still have a long way to go before they can be even considered good enough for waifu sex, they might be able to escape the uncanney valley someday. Hopefully that day is in the near future because robots are neat.
Also to the people who are saying that VR is/will be to expensive to be of use to most of us, technologies like this (if they popular enough) go down in price significantly. If VR does get adapted enough, it would still take it a couple of years for it to get cheap enough but it most likely would.