I experience something similar (sort of). My husband is a physician, and I am often on the receiving end of comments like, “Is that a diamond watch? Must be nice to be married to a doctor!” (when in reality, I bought that watch for myself (on sale, of course!) to celebrate getting my first big job after I graduated with my PhD, long before I ever met my husband). Or, “You took a 6 month unpaid leave of absence to stay at home with your baby? Wow, you sure lucked out getting married to a doctor!” (when in reality, I had been planning ahead for that leave of absence for over a year (before I even got pregnant!), and had set aside funds from my own paycheck for the express purpose of replacing my income for that period). Etc. etc. etc.
Basically, some people seem to assume that my husband is some kind of fountain of money, and therefore must be footing the bill for all aspects of our family’s life (even when they are aware that I am a full-time working professional with a 6-figure salary). These comments are irritating to me in the same way as the comments I occasionally get about how “lucky” I am. That is to say, they completely discount my own *years* of effort (earning, planning, saving, prioritizing, etc.) and attribute everything to some external factor. I agree with one of the posters above; I think it is a case of (for example, a co-worker who can’t seem to manage her money effectively) thinking, “I could never afford a vacation like that, and we make similar salaries, so someone else MUST be paying for it.” But this same co-worker sees me bringing my coffee in a travel mug from home each morning, and my lunch in a sack from home each day, and never connects the dots between my behavior and the nice vacation.