As a man I have to admit I have never asked what the status of a relationship is. On the other hand I have had women ask; "What are we?" or "Where are we going?" It's usually within the first 3-4 months.
One year is a long time to be "floating along" and not knowing if you're in a "exclusive relationship" or "in love with each other".
Generally speaking this is much more common with a young person as they may still be dreaming about having their fairytale wedding.
Where as people age 40 and beyond have probably been married and divorce before. They're in no hurry to rush down the aisle again or comingle funds. They may be looking out for their grandchildren.
I believe some people are just uncomfortable with initiating "the talk". A part of them is comfortable with the way things are but another part wants to "know" there is a mutual (emotional investment).
Oftentimes people also have a hidden timeframe of events they expect. If things aren't "progressing" on schedule they're nervous.
At the 3-6 month period we should have met each other's inner circle of family and friends as well as said; "I love you".
After 1 year we should be talking about building a future together whether that entails becoming engaged or living together.
For some people when there are no more "milestones" they become disenchanted with the relationship. Many feel anything short of marriage is a "dead end". It's all (psychological) though.
No one loves anyone more because their "title" changed from girlfriend to wife or boyfriend to husband. The commitment comes (before) the wedding. Others are afraid of "investing time" in a relationship that ends and yet our divorce rate hovers around 50% thus proving exchanging vows is no more of a "real commitment". If someone wants out they're going to leave regardless.
Communication is the GPS for relationships. It lets a couple know if they're "growing together" or "growing apart" as well as if they want the same things. I think it's best for someone to state how they feel and what they want rather than cowardly asking in a round about way to get an idea of their mate's feelings.