Is that a US thing? I know this advice is given to teachers and such here, but colleagues? Quite a few of the people who worked at my company had relarions and/or married (with kids a lot of them) because of office flirtations; some love at first sight. I guess if it is a common thing then yours is good advice but I would not exactly like to work in such a paranoid environment, especially with people who should be my peers.