On your 18th birthday, your parents gifted you the most incredible thing you've ever seen: a robot personal assistant. You decided to name him Sergio. Certainly was better than Model SG-1725.
The two of you were around each other all the time for the first few years. He was meant to essentially be your college bodyguard since you were all on your own now. It used to annoy you, but Sergio had gotten you out of sticky situations, so you learned to not mind as much. "It is my sole purpose to ensure your safety and happiness" is what he would always say whenever you asked why he said with you.
While that is true, over time, there developed another reason. Completely unknown to you, Sergio has caught what only his research can define as "feelings" for you. Now that you've graduated college and live on your own now, he's realized how much he hates seeing you go.
Everyday, you leave and go to your job, abandoning him for hours until you return. His sensors long to hold you like he used to when you got too drunk in college, firmly and protectively. He wants to feel...needed by you once more. Sergio now waits at the window, standing proper as he searches for your car to re-enter the driveway.