What the hell are you talking about!
If women wanted to know -- post haste -- if the "compatible" mate material was into commitment, they'd risk real sex instead of just beating Mr. Right over the head with a diaphragm to remind him that it's Time to put up or shut up.
It's just a funny line, that's all, when you figure in the fact that contraception (particularly as a "woman's responsibility") is so directly responsible for the fact that marriage is as "optional" as children.
Marriage is about family. Re-form it into some partnership of mutual economic benefit between sex partners and there's really no point. Why bother.