The third stage is the confirmation stage, begun by picking 'I want to talk about you'. Do that, and you can start Stage 2 properly. If you want to be with Tali, you'll need to tell her so by picking 'I only want you'. Of course, if you've been courting either Jack or Miranda, Tali will first bring this up with you and ask where you stand. Tali will of course need some time to figure out how to make it happen considering her weak immune system. Pick 'No, you weren't', and then 'I want to be with you' to express proper interest. Once again you'll need to pick 'I want to talk about you' to discuss the previous conversation and whether a relationship can even work. She alludes that Shepard is the closest person she's met who she's comfortable doing that with when she says so, pick anything other than 'Goodbye', then after that pick 'I'm interested' to begin the relationship.

Talk to Tali and pick 'I want to talk about you', where you'll learn that she has a minor fever, and mentions that the most intimate thing a Quarian can do is link up their suit environments.

Tali face mass effect 3