That's pretty much what happens to people who are not empathic at all. At some point they suffer backlash and then to compensate, they go full thinking mode, so its more of a understanding by thinking than empathy by feeling. Saying this as an autistic vet.Shima claims to not be much of an empath but honestly I think she is a really good one. The amount of care she puts into what others around her think and feel is beyond what most people would do.
Adachi would make that awkward for Shima's friend. She'd be doing something and I think Shima would rather avoid that. Besides Tarumi having a real crush, you can't have Adachi regularly reacting negatively to Shima having friends.Bring Adachi along, why not? Hang out with the three of you.