[inquest]

Why not make it the man's responsibility to have her sign the paper.

Because the law assigns custody rights to the woman. Rights and responsibilities should go together.

[Clara Lou]

If a man wants the right to enjoy obligation-free fornication, it should be his responsibility to have the paper signed. Get it? Right... responsibility...
(Actually, it makes no difference. Either of the two fornicators pulling out a legal document to be signed would put an end to an awful lot of fornicating. Nothing like a little cold, hard reality for putting an end to the mood.)