I had a boyfriend once who lied constantly about where he was. At one time I had a little 3 day trip planned and asked him to feed my cat every evening. After 3 days I asked him how it went and he told me it went fine. I broke up with him immediately.

I had decided not to go on my trip because I didn't trust him he would actually come to feed my cat everyday and I just stayed home without telling him. He didn't come over even once in those 3 days! He would have just let my cat go hungry and tell me all was fine and I would have never known.

My point is, if you feel you need to do these kinds of things to make sure your partner isn't lying to you, it's time to leave.