It was sarcasm as you said 'loosing' instead of 'losing.' Not very helpful I know.
I have seen my iPhones forget Wi-Fi info for a previously visited hotspot but it has been rare. I just reconnect. I am sorry I don't have a solution for you. Perhaps visit an Apple store for help.
Edit - thinking about this, if it happens to two phones the fault sounds more like the router you're connecting to. If you have the ability, make sure it's running the latest firmware and/or reset the router.--