Can you have a relationship with someone who is separated?

Yes, you can date someone else after you separate from your spouse. There is nothing illegal or wrong about dating while married and waiting for your divorce as long as you are living separate and apart.

Is it OK to date a woman who is separated?

If youre considering dating a woman (or man) whos married but separated you should reconsider. As strong as the attraction may be, the likelihood that the relationship will last is small. And taking that chance will put in you in a very real position to be hurt.