Ah, the delicate matter of… inadequacy. Very well, I shall address this unfortunate scenario with measured magnanimity:

• If your companion’s nerves betray them-incessant whining, trembling, or other displays of vulgar melodrama-we may condescend to grant a second trial. May. Improvement is mandatory.
• For unaltered males whose enthusiasms prove… unseemly*: A second attempt is permissible only after a minimum one-month post-castration grace period. Assuming, of course, you’ve attended to such basics of canine decorum.