Hya Paul. It's hard to guess what's happened, but in my experience, the UV sealant needs to fully cure before exposure to wet weather. I suspect that's the crux of the problem. The current weather conditions (cold and damp) aren't very conducive to obtaining a fully dried/cured film. It sounds like the finish here is a water-based formula, so the effect of rain on the uncured film is to re-dissolve it.
As to removing the now damaged finish, I suspect you'll have more work ahead. I suppose it might remove completely using hot water and a detergent. Maybe try it on a small area first. If that makes things worse, I think you'll have to let it cure fully and re-start from square one.
I'd recommend using a separate finisher laquer from the type that often comes with the sanding kits. These seem little more than a wet wipe. You can get aerosol applied UV laquers which are non-aqueous but do require reasonably warm and dry conditions to fully harden. Always read the instructions. This is the stuff I used around eighteen months ago and so far so good.
TC