[greenail]

The problem is not bad intentions or selling your information.

The problem is that they copy it into a DB and it is a globally unique identifier. Once this happens you have lost control. You can never ungive that GUID. Your only recourse becomes spam filtering or migrating to another email GUID and waiting until the new one gets leaked all over the intarwebs and then doing it again. Phone numbers are even worse.

The solution is fairly simple, as discovered by the OP. Don't give out the same GUIDs when you sign up for an online "relationship".

It is a shame this pattern exists, people should stop designing accounts like this.