sweat problems  

I say, don't panic. It's a...
I say, don't panic. It's a bummer about your sofa, yes, but you're really just a vicitim of your own PH, which can change over time and is most likley not a hallmark of some impending illness. It would also make sense if you and your fiance share this characteristic, as you probably enjoy the same diet, excercise routines, habits, stress, etc. Also, dehydration, sodium levels, smoking and alchohol consumption can have a dramatic effect on sweat.
I knew a woman once whose sweat broke down the elastic in her clothing, and ate away at the paint on her car door where she hung her elbow out the window. There was/is nothing wrong with her, simply heavy alkalais and acids in her sweat. The only thing you have to worry about is hypochondria by proxy. This is so silly I won't even make the usual disclaimers.
As for the sofa--maybe a Scotch Guard treatment would help as a preventive measure in the future.

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Of course Austins 102 temps dont help!Im pulling out all the feathers I can do without...possibly drink copious amounts of water?

Yes, Austin's heat is...
Yes, Austin's heat is dreadful. I went to Barton Springs this weekend. For those that don't know, BS stays around 65 degrees all year, regardless of the weather. It's quite a shock to go from 102 degrees to 65 degrees in one second. Shiver!
Thanks to everyone for their comments and suggestions. I have yet to try anything on the sofa yet, but I will hopefully in a week's time.
I do think I'll pass on seeing the doc. I feel fine, and this has been the case for years ... even for my fiance before we met. Maybe on my next visit I will inquire ... I would like to know what would neutralize it.

Dont be scared
Just read a medical article and condition is harmless. You are not going to die or anything. I just recently had major surgery, NOT for this, but something in my body system changed and now my sweat stains my shirts bright orangy yellow across the chest and shoulders. Yes it freaked my wife and I out but after reading the article it eliminated my concern.Sweat comes in many different colors. Check out Eccrine and Apocrine Chromhidrosis. I am going to mention it next time I see my doc as he is an Endocrinologist.

Whitespike
You never told us how this issue played out for you. Did you learn anything beyond what's presented above ?
Maybe it's none of our business, as they say . . .