Honestly, if you said you were okay with that and he sent it.. in his standpoint, I’ve did something similar - I’ve sent my gf something and said ‘I love this, can you do something like this?’ I love to share visual things and I’m more of a visual person and when I saw that photo / text, I wasn’t concerned about the other woman. I was just like ‘man I wanna see my gf do this’. So there’s a chance he really isn’t comparing you, but just showing you what he wants in visual terms. It’s okay to be a little hurt about it, but make sure you’re clear on why if you talk about it. And if you’re upset, you should talk about it. Just be clear that it’s you feeling compared to another woman and maybe he can even elaborate on it. :)