Is a 50 year-old man the right age for a 37 year-old woman?

My older sister is 37 years old and she's briefly engaged to a 50 year-old man. They're proceeding through to the wedding within a couple weeks. They're both after tax reductions, government and medical benefits (the rights to visit your spouse in the hospital and make medical decisions if needed) and to be included on health policies.

Neither of them ever had kids. Is a 50 year-old man the right age for a 37 year-old woman? Several people think he's too old for her. Is he or is it right?

Updates
1 mo
The guy obviously looks just about his age and he's sure not attractive. My sister looks younger than her age but we can't forget she's really 37 and not very young anymore.
Is a 50 year-old man the right age for a 37 year-old woman?
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