Google + / Hangouts

Does anyone know of there SO/ husband using these to talk to people he shouldn't be? I just discovered my husband has an account. He's working now but I plan on asking him when he gets home face to face. The weird thing is he has a iPhone so these apps don't come already installed and I have never seen them on his phone before. But I have been having suspicious feelings for awhile..we aren't "unhappy" but we do have a toddler and I'm pregnant so that can add stress on a relationship.