Hi W75 and welcome to the forum. Sorry to hear that you are having difficulties.
If you and your partner were to separate, this would have little effect on your IVA as presumably you have already paid over the lump sum. Your partner's UVA - which I have to say I find odd that she was required to pay £100 per month for five years, as the costs of running that almost exceed any benefit - will continue, but she could use her share of the house sale proceeds to try an early settlement. After agents and solicitors costs, there is unlikely to be too much left.
Regards, Melanie Giles, Insolvency Practitioner for over 20 years.
For further details contact me at
http://www.melaniegiles.com and view my IVA blog at:
http://melaniegiles.blogs.iva.co.uk