I can absolutely see the "metal" and padded "leather" items go hand in hand, but the cod-piece design doesn't convince me yet. It's diamond shape clashes with the organic lines and the pointed tip looks unhealthy, especially in that place. Probably won't help to convince your girlfriend that armor making is the most amazing hobby, either... 
Yes, in fact the area around the belt is the one I'm not really sure about. First, the armour looked kind of unfinished without somthing to protect the waist, but I idn't want a kama or something, but on the other hand a plate for my nuts isn't my favourite concept either xD
Last time I thought about this problem, I accidently found a picture of Sub Zero in my room, that inspired me to have
some kind of huge belt-buckle with a Silk on the downside. But right now that I googled the picture, I recognize he used a chain-thingy, what makes much more sense and also looks awesome! I remember to have seen a tutorial for this made by you, Tomoe.
So I doesn't really like the diamond shape either. It was just my first idea and I got no other ideas yet. Maybe the same shape Sub Zero has would be the right thing, but it's protecting his belly also, where I already have my plates...
I'm pretty sure my girlfriend would help me if I asked her, since she's the one who made me begin costume-making, but I prefer to do the most work myself, so I can criticize every part of it just like I want without blaming somebody else.
