hetero husband watching wife with a woman, why does it feel different than watching her with a man

genuine question for other hetero blokes whose wives are bi or bi-curious. weve been ENM about 3 years, ive watched my wife be with other men loads of times and i love it, hotwife dynamic basically. but last month she had her first proper time with another woman and the way i felt watching that was COMPLETELY different. not jealous, not threatened, just... reverent? like i was witnessing something that wasnt for me at all and that was somehow more intimate than any threesome weve ever done. afterwards i couldnt stop holding her. anyone else had this? whats actually going on there psychologically. the bull stuff feels playful and fun, the woman stuff felt almost sacred and i dont know what to do with that word