I guess we are in the "open book" club.
My phone is also my "work" phone (paid for by my employer) - so I advise anyone corresponding with me that should automatically assume that my boss could read their txts. Given the nature of the technology (i.e. encryption issues, etc.) I think it is wise to behave as though ALL txts/emails are public knowledge (on the other hand...I am hyper-cynical in this regard).
If MrS's or Dude's phone goes off with a txt...I would check it to see whether I should wake them up to respond or let them sleep. I don't think that it is wise to assume confidentiality of TXT or email unless you have specifically negotiated that with someone. You have NO idea who has access...unless you ask (and even then, they could be wrong, this is the digital age people...there is ALWAYS a record