I would not have a problem with her being impressed. He will not be the first guy she has been with since we were married, I find that generally the comparisons are favourable to me. Even if the guy is awesome, I have a lot of experience pleasing her, and a lot more motivation to do so, which makes a difference. And I have a giant ego, so I look at her being with another guy as an opportunity for me to look good by comparison, I am not insecure about it.
Love does not always have to be about ownership, it can be for some people, but it isn't for everyone. The fact that she can be with other people, but chooses me, is gratifying, I prefer that than to keeping her guarded and wondering if she would be happier with someone else.
And just for context, it works both ways. Recently we celebrated our wedding anniversary, and she said she wanted to have lunch with me in the restaurant where we had our first date, then have sex in a hotel in the afternoon, so I agreed. Her anniversary surprise for me was that she brought her friend (attractive MILF, tiny, brunette, fit, big tits = 100% my type), she joined us for lunch, then we all had sex in the hotel, the three of us. So if her fantasy is to be auctioned, who am I stand in her way.