I might have thought over-watering was the cause but as it seems to be one rose only, I agree, this is very suspicious.
You could cut an affected branch off and scratch through the cambium layer...or if thick enough, a cross section - wilt shows up as darker streaks and also has a musty, mushroomy, yeasty smell. Then check the soil around the crown - are there signs of a mycelium, hyphae...or even fruiting bodies (bootlace black strips)? Whilst you can treat the soil with armillatox, there is no real cure for this - my cercis is also slowly dying...and yet a moyesii rose, right next to it remains unaffected. I think there are sterilising methods but this usually involves replacing all the soil in that area...while I have chosen an easier route by growing things which are not susceptible. As I have not seen this in a rose, I do not feel qualified to offer any truly helpful advice...but I sympathise, I truly do, as it is a horrible drawn-out misery.

You say " a deck full of roses". Does this mean they are growing in pots? I wonder, if this is so, whether the potting soil around this particular rose has become water repellent further down in the pot, as this has happened to me on occasion. In this case I use a re-wetting agent and if necessary, water retaining crystals inserted down into the root system to stop further water loss. I really hope it is nothing worse.

Since VW is a soil-borne disease, I would''t expect in in a pot with soilless medium, but it's possible. If the plant is infected, it won't help to change the soil. I have had VW on a couple of roses, and believe it or not, the plants fought it off after a season of losing one cane after another. Tips wilted and leaves died from the bottom up with partial yellowing, often one side of the leaf yellowing first. Then the cane died. Unlike VW on most plants, on roses it usually doesn't produce a dark ring on the inner bark.

Bacterial blight of rose is another wilt disease. You would need a professional diagnosis for either.

Check the upper stems for borers.

I have also had the drainage holes get blocked in a pot, and the rose was sitting in soured water. The symptoms look much the same as not enough water.

Ugh so my camera battery died so no photos as of yet.....Thanks everyone FLrose, Michael, Ozmelodye and Cam for the sharing, it's really helpful! I think I will treat the rose for the simplest problem first. This rose is in a pot that has a bottom saucer so I removed it just to see if this helps creates better drainage. I really hope thats all it is but I did notice a seedling I kept next to it has a few leaves that have turned brown as well :/ ....Just in case I'll try to separate them both from the others.....I really hope this is on the less serious side.