Can someone fool me with their location on 'Find my iPhone'?
the guy ... knows how to google things very well.


Which is not the same as being a competent software engineer, and that's what you will need to be to send false info to Apple's location services.


  Sometimes I see her call log and see calls from her parents even when her find my iPhone location is at home and her parents are at home.


Means nothing. I know several people who call others in the same house. Easier than yelling down the hallway or to the back yard.*

The easiest way to appear to be elsewhere is to get a second device. An iPod will work just fine. Set it up with the same Apple ID and select it in any of the location services apps. That works for Find My Friends, does not work for Find My Phone. Since you said "Find my Phone" you are either using the wrong term, she has a phone you own, or you have access to her Apple ID?

Sounds like you need to do some private detective work. Just drive over to where she is and see if she is there.


Funny of the Day:
Girl is watching a movie with boyfriend. Hears incoming text on the phone, which she left in the kitchen. Gets up, goes to phone which reads "bring more chips back" sent by boyfriend who is still on the couch.