OK. So there are larger issues in the world than say... relationships and dating. But still...
There's no other question in the world that irks me than "Why are you single?" I don't like it if it's asked of me. I don't like hearing others asked the question. So, I don't ask that question of people. Not that I'm defensive about currently being single.
But, the question assumes many things that just seem weird to assume: 1) that the person being asked has Godly powers to magically put him/herself in a dating/romantic relationship; 2) that despite all the good qualities of the person being asked the question, there must be a flaw in the person being asked that s/he doesn't admit; 3) that it's a right to be in a dating/romantic relationship, rather than a privilege; 4) that one should always be in a dating/romantic relationship.
I heard it over the weekend. One of my students came to me, one of the 1988 boys, and said one of his classmates asked him the same thing. Said it made him feel like there was something wrong with him for not being in a dating/romantic relationship. I advised him not to worry about other people's assumptions about his dating/romantic life. That contrary to popular belief, there are more single gay men than those in long-term (or even short-term) dating/romantic relationships (I heard it at some speech recently, I might be incorrect... if you know, please clarify for me/us)
When you are single, how do you feel when asked "Why are you single?" I can tell you, I start to feel defensive, but then respond with what I really feel, which is, "I'm happily single, but open to the possibilities."