It's interesting that being able to read someone's emotions would make dealing with people exceedingly much easier, even to the point of confessing love since you would know if the other one likes you back or not. Yet in a romantic relationship it might actually be a burden. Superficially it would make it easier to do things the partner would find pleasant, but that might turn into a poison, just like it has been a "poison" that had made Shino a social chameleon that can get along with everyone. Just like before, in this chapter she admits to herself that it hasn't made her an admirable person. If you live in a relationship for years and decades, it can't be based only on pleasing the partner or being afraid of doing anything they don't like. That would keep it too superficial to last. At least that's how I see it, and it might also be what Shino is worried about, since that's how she has lived her life up until now.