How can I be notified when my boyfriend tracks my iPhone?
Unfortunately no,

Find My Friend is a one way communication style app. It allows you to notify people of your location and see their location. Also, you have the ability to notify someone when you arrive, leave a place, or you can send your current location. You can also be notified if someone lease or arrives at a place (and they can do the same), however it does not have the ability to notify you if someone requested your location.