They have that, it's called Singles. Since technically if you aren't married you're single. And singles date and get into relationships. Chances are your best advice will come from Singles anyways. It has a core group of people, a number of which are in and out of relationships, who are likely to give you the most balanced advice of anywhere on the site.
And whether a person is single or married chances are they have dated at some point. So i'm not sure why there needs to be a section devoted to people in relationships to give advice, when most people have been in relationships and can give advice. One doesn't need to be in an active dating relationship to be able to help.