The job ad says that knowledge of a foreign language, Russian in this case, would be a plus.

You don't know Russian and you didn't mention your girlfriend being a language teacher, so if a bilingual speaker saw that they may have a bit of a laugh but it wouldn't do anything except make you look overeager to land the position.

Not necessarily negative, but a bit naive perhaps.

The job ad says that knowledge of a foreign language, Russian in this case, would be a plus.

You don't know Russian and you didn't mention your girlfriend being a language teacher, so if a bilingual speaker saw that they may have a bit of a laugh but it wouldn't do anything except make you look at best overeager to land the position.

Not necessarily negative, but a bit naive perhaps.