If the elders "advise" someone to stop dating, courting, etc. anyone, and there is not a stopping, yes, they can, for "brazen conduct."
(Brazen conduct is anything not covered by anything else.)
If a Dub up and marries someone without having been advised otherwise, then they should not be DF'd, but they will not earn "privileges" indefinitely.
(This is, of course, predicated on the Dub being "scripturally free" to marry.)