Your wife is definitely enjoying these photos sessions even though she may start off a little hesitant and has some absolute rules, for whatever rationalization she maintains - as you say: women.
She seems quite willing to remove clothes specifically so you can take photos, knowing many will be sent to your friend, so in a way she is posing for your friend! That she wanted to change her top so it would match the color of those lace panties shows she wanted to look good and color coordinated for your friend. So hot.
Just remembered you mentioned she dated him a little before dating you, so she may be showing him what he missed out on having, or maybe not... Who knows?
Hope she does buy some other lace panties, but you could just go and buy some for her anyway, and then you could get the style you like. Could also get smaller, bikini style white [and other colors / patterns] cotton ones that would still have that innocent look that you like, would be "comfortable" for her as not much of a change. My wife went from smaller cotton, to string cotton, to some lace, to mostly lace and some thongs, to now mostly lacey thongs. Nothing I did but she did presumably on her own, and something I fully encourage and enjoy; especially the thought of others accidentally, or maybe not so accidentally, getting to see glimpses of lace and what is encased therein.
Was there much wine involved during either evening? You made a point of it in other posts, but no mention this time... Sounds like it played less of a role which is wonderful! Means she does not need to have her inhibitions lowered as much and is more comfortable sharing her sexy bod. In time, the 2 boob rule and others may (will!) fall away as well! Keep taking photos and pushing that envelope even though you might not send them immediately to your friend. You can always send them later if he cannot look at them while on vacation. And you might shift the scene some by taking fun / sexy pics in other locations: maybe sitting at a pub, or along that river that was shown in in your balcony pics; anywhere others might also see something, even if no one else is in the immediate vicinity. Especially as it is getting warmer she can wear little to begin with! Keep up the great progress!!