One of many "family secrets" the Scienceists don't like to talk about for very long before changing the subject is the near total non-detection of "gravity waves." And they've been looking, looking, looking for a long time, in some very clever ways. Like you, it's occurred to me also that entanglement may be hold the answer to that very inconvenient problem. The attraction all mass hold to all other mass (with a strength proportional to the inverse square of it's distance - to the present limit of our ability to detect - see "The Pioneer Anomaly) might well be a remnant of some quantum state that existed in the primordial singularity.
Part of the problem is that gravity is so weak, I had a good long talk with an old physicist friend of mine, what if gravitation is repulsive at long distances? IE, it is ax2-tx3 where t is a very small number.