In order to get my girlfriend join Stack Exchange, sometimes I write questions using her account and upvote these question with my own account.

I feel this question is going the wrong way...

I write these questions for her to show her how to write good questions, and upvote them because I think they are good.

You really shouldn't. You should refrain from voting on your 'own' posts, posted under another account basically. I understand the thing you are doing here, but you should let the community vote on such posts.

And yes, it will trigger voting fraud scripts, as it should.

In order to get my girlfriend join Stack Exchange, sometimes I write questions using her account and upvote these question with my own account.

I feel this question is going the wrong way...

I write these questions for her to show her how to write good questions, and upvote them because I think they are good.

You really shouldn't. You should refrain from voting on your 'own' posts, posted under another account basically. I understand the thing you are doing here, but you should let the community vote on such posts.

And yes, it will trigger voting fraud scripts, as it should. We really appreciate you want to help users to become a member here, but such voting patterns are hard to distinguish from classic serial voting, and it even might end you up with the accounts merged.