BTW, I think it's a really good sign that Sunshine was able to say to you guys that she felt like she was being treated like a piece of meat. So often, we see "thirds" come here and talk about how they just suck it up and take all kinds of stuff from couples that made them feel uncomfortable. Unfortunately, they usually only start asking questions when it's at the breaking point.
Sounds like Sunshine has the ability to clearly see when weird shit is going down. Thank goodness you met someone who has a sense of self and is unafraid to express herself when things don't feel right! Now that is a blessing, if you are able to get past whatever embarrassment, jealousy, or indignation you may feel about the situation, because she can be someone in your life who enables you to look at stuff that needs to be looked at.
The world opens up... when you do.
Oh, oh, can't you see? Love is the drug for me. ~Bryan Ferry
"Love is that condition in which another person's happiness is essential to your own." ~Robert Heinlein