Brun being fascinated by Millie's body does not preclude a later relationship. If anything, Brun's active choice to be there for her friend when she's obviously fascinated by the less "morally supportive" aspects of being there shows that she's making the decision to build this relationship. It's those decisions, including Millie's decision to let her observe the procedure, upon which relationships are founded. There's also nothing unhealthy about her fascination. That sort of fascination is what drives innovation, so the robot chassis would not be around if it weren't for that fascination.
There are many pernicious, I think, practices, surrounding dating. Assigning a negative value to showing interest in the body, is among them. My favourite intimate relationships, were with partners, who---mind
and body---were interesting and interested. Not necessarily sexually. The interest in the body, enhanced interest in the mind, by having us together more. I think it's a hasty criterion, of not showing enough interest in the mind, before body.
Perhaps they're in a rush to be mentally intimate with someone. In some cases, that may be reasonable, but I suspect that in many cases, it's that they're inexperienced, about living alone.