"deficiency" can be used in a lot of contexts, but it is a technical word, so using with "love" would sound strange, although people would know what you mean. It is normally used when referring to something scientifically quantifiable (measurable). "A deficiency of dust in the air kept the moisture in the air from condensing into rain." Having said that, it could be used in the way you suggest if you are trying to be funny (and they know you are trying to be funny). It's not offensive, just out of the ordinary.