Why are men so reluctant to get a vasectomy?

We got a message from a woman whose husband keeps putting off getting a vasectomy. She says that she cannot continue to stay on contraception as it plays havoc with her hormones but he just keeps cancelling appointments for getting it done. He’s in his mid-thirties. He went as far as saying “What happens if they get split up in the future and he meets somebody else who wants children”? Why are men so reluctant to get a vasectomy?

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