who had never married, let alone gone on a date.

[sitifan]

The idea of revisiting the pain was not well received by Kathleen, who had never married, let alone gone on a date.
http://www.wmzyw.com/shiti/yingyu/2020-03-16/32731.html

The clause in red is semantically odd, isn't it?

 

[sitifan]

It isn't. What made you think it was?

The phrase "let alone" is used to indicate that something is far less likely, possible, or suitable than something else already mentioned.
https://www.lexico.com/en/definition/let_alone

I think "marriage" is less likely than "going on a date."

 

[emsr2d2]

I have to agree with you from a logical point of view. It would be more natural to say "She had never [even] gone on a date, let alone married!"

 

[Charlie Bernstein]

The idea of revisiting the pain was not well received by Kathleen, who had never married, let alone gone on a date.
http://www.wmzyw.com/shiti/yingyu/2020-03-16/32731.html

The clause in red is semantically odd, isn't it?

Yes, it is. It's backwards and doesn't make sense.