I have cats who suddenly, after months of walking by the same object, decide one day that instead of it being a harmless object it's actually a new toy. I've had L.S. for 6 months, and two days ago he found the phone cord for the first time and bit clean through it. Or Merlin suddenly deciding the fox beenie baby on top my monitor is "the thing" to try and play with. I've had him for almost a year, and he just started this a few weeks ago! I'm assuming that the cats are getting bored and have cabin fever since I haven't been able to open any windows for them to lay in.
Um, they make spray deterants that you can buy at pet stores. I have no clue if they'd ruin a couch or not, so you'd want to read labels and test it somewhere where it can't be seen if it's ruined. I just bought a bottle of Bitter Apple and sprayed the phone cord down and I haven't seen L.S. go near it yet, so I don't know if it worked. I know there are a couple other brands out there. I found them mixed in with the stain and odor removers in the dog section.
Hope this can help!