I feel a marriage should hold no secrets, if my husband wanted to take my phone and do whatever with it I wouldnt worry because I have nothing to hide. He does not feel the same way which is understandable and I respect that.
Be very careful with snooping. it can cause a huge rift between you and your husband. be honest and open with him and let him know you're not going to let an emotional relationship start between him and the co-worker.
Sorry to sound so serious. :)
I agree with this.
My first thought was maybe he was venting some of his frustrations to her about your marriage - then deleted them so you didn't see some of the things he was saying. While it's perfectly normal to have someone to blow off some steam to, I don't find it appropriate for him to do it to a female.
The reason I say this is because I vent through texts to my girlfriends. It's about stuff I can't change about FI, for the past two years he's had extreme back pain that the his docs don't understand, which leads him to not contribute as much as I would like. Telling him over and over again how frustrated I am about it only makes him feel even more terrible, making his disability related depression even worse. So I've learned to vent about it to friends.
I agree with being open, honest and transparent about things in a relationship, but sometimes one person's feelings about something that can't change can actually do harm.