I'd say it was damaged by the weather. Rhododendrons vary in hardiness, some fairly tender ones are sold even at garden centers - you can't assume one will be hardy locally just because it is offered at a local garden center. Many outlets display them with hardiness expectations indicated, so you can often get an idea right at the start as long as you know what minimum temperatures are likely on your site. There can be considerable differences between properties in fairly close proximity.
Whatever the exact cause it looks severely damaged and should probably be removed and replaced with something else. Unless the roots are dead re-growth from lower down on the stems may be possible, but it will take years to recover the appearance it had before the cold spell.
A number of years ago our strata "landscaper" fixed our sorry Rhodos by cutting them off almost at ground level. (I had a word with him over that!) A few years later they were actually growing and blooming on all sides, and looking at least respectable, and worth persevering on. Not something I'd recommend, but those rhodos were HARDY!
Some kinds more vigorous than others, and not all are able to sprout well from old wood. Another thing to be aware of is that where mildew is present trunk sprouts may be hit worse, fail to persist and develop unless kept sprayed.
This is encouraging news. One of my rhodos--Virginia Richards-- had some interesting damage this winter--it is two feet in front of the dryer vent, and altho' that hasn't bothered it in the past, this winter it seemed to be burning the leaves, and some of the Johnny Bender as well. I lost well over half the leaves, and it didn't bloom as well as usual (what a surprise). But it has leafed up some since, so I'll give it another year before deciding if I need to move it. Thanks for the update Burnaby Jo.