It comes from the highly sexist and patriarchal notion that a woman’s value is based on what kind of man she can get, so we should be constantly striving to find a man, and if we’re not (or we can’t), then we’re failures, weirdos, or lesbians.
Fuck the haterz, man. You do you.
(But if you’re asking whether her statement was indeed offensive or whether it would be within your rights to say something to her about it: yes and yes.)