My guess is that somewhere along the line, either just before or just after you bought it, it got quite chilled. It had probably been somewhere quite sheltered at the GC, so the leaves were a little tender. When it got chilled the leaves were damaged and died.
Hopefully it didn't get chilled enough to damage the main stem or roots - it is fairly hardy, but if plants are in pots their hardiness is reduced, ditto if they've been in a sheltered environment and they've put on some soft growth.
If your patio at the back is south-facing, then your front porch faces north - am I right? Is this a fully glazed porch or open to the elements? I'm worried that it's still too chilly at the moment, especially if it's feet are quite wet. I'd be very tempted to take it indoors and put it on a southfacing windowsill - let the pot dry out a bit and see what happens - if it revives then, when the weather warms up a bit, harden it off gently as you would tender bedding plants, before putting it in the garden full time.
As for the situation - I think it will cope with either situation provided it is introduced to bright sunlight slowly - tender lush growth will scorch if put in bright sunlight too soon.