Night crawling is bad?

The leading character is a virgin, reserved, \”otaku\”. His work is home security.
By strange accident, his father remarried and he got a new family.

…My sister-in-law looks at me really coldly.
However, I am panting and suffering with mental anguish over the sister-in-law in my new family.

I couldn’t stand it anymore so I decided to do night-crawling on __/__/20__.
If I am found out she will look at me even more harshly, and treat me as sheer waste.
I need to have sex with her without being found out.