Why this difference?

Was having dinner with a friend a few days back. Some discussion started bout marriage. Then it veered into non marriage ie remaining unmarried.

My friend said its still ok for guys to remain unmarried, but its not at all expected from girls (in India).

Why?

If in our society we can, though not readily, accept a man deciding to spend his life alone, then why should the rules be different for a lady?

I know both times and mindsets are changing in our country, but we still have a long way to go before we can actually boast of accepting the equality of the sexes.