I'm concerned about my privacy in my bedroom....

My male roommates friend is staying here for a few days. He's been in the house for about a week. I've noticed he always pretends to use the bathroom whenever I'm in my room. I've caught him listening to my conversations with my roommates twice, and have heard him listening to my conversations with my partner when they called me. I've been locking my door but it's a flimsy thing and I don't think it would be hard for him to pick the lock. I've talked with one of my roommates about it and he offered to move his friend but I don't want to kick him out or ruin his relationship with his friend. I've also been staying in my room with the door locked to avoid him as much as I can. <br><br>I'm a 22 year old woman.