In His Arms by M. Stratton

After years of living in Los Angeles, Mya Lawson was tired of the pressure and the pace. Deciding it was time to move on, she chose Roslyn, a small town in Washington State not far from Seattle. It was a town that a high school friend had loved, and she thought this little up and coming hamlet would be the perfect place to start over, and enjoy life for a change.
Nate Robbins and his sister founded the high-tech Vault Security in Roslyn. Between the two of them, they were the leading innovators of renewable energy security systems: homes for people who wanted all the bells and whistles of smart security while being able to live off the grid–untraceable.

When these old best friends run into each other again, they realize their feelings are very different now and their passion quickly heats up.
…But in the shadows, someone is lurking, watching. Someone who has been saving himself for someone like Mya his whole life. Someone who will do whatever it takes to possess her.
Even murder.
What do you do when your smart house turns on you and there is no escape?