DeMarco Murray -- Engaged To Soap Actress

Who says the Cowboys can't close?

DeMarco Murray just popped the question to his longtime GF Heidi Mueller ... and good news for the running back, she said 'Yes.'

Mueller famously portrayed Kay Bennett Crane on "Passions."

DeMarco and Heidi have a daughter together.

It's the first in a series of big moves for the Dallas star -- who's set to become an unrestricted free agent in a couple of weeks and may have to leave Big D if the Cowboys don't come up with a big contract offer.