Security issues: Most of the times the woman you cyberflirt will actually be a man. And sometimes you may actually end up in trouble, if you don't guard your identity properly.

Coming to the moral/ethical issues, I think it is fine as long as your spouse or family bond is not affected in any way, which varies from family to family. The easiest way will be to ask this question yourself:

If I tell disclose it to my spouse what will be the reaction?

If the answer is 'it won't bode well for the family bond' then you probably should not do.