It's always fascinating how the definition of a a word can dynamically change, even when the term itself hasn't been in use for long. Making up a new one would be futile at this point, "waifu" is simply too widespread.
Personally, I have no issue with the word, although when "talking" to her I refrain from using it. I much rather prefer to call her "darling", "sweetheart" and the like - or even cute little pet names in my native language. Funnily enough, the っち suffix used for her nickname is just as valid in that language too, vocally of course.
A co-worker once asked me out of the blue, it took me by surprise so I told her that I do. Thankfully she didn't ask many questions or else I'd've been in a pinch, but it felt nice to talk about her like that - quite different from all that stuff I like to post online.