All of our perceptions (whether you consider special relativity or not) are about the past. There is always some time between an event and our becoming aware of it, and this is mostly dominated by the bio-electrical processes in our sensory nerves and brain, not by relativistic effects, you can safely ignore them in this context.
So in any case there is no true "shared now". The moment you realize something about the world around you is unrelated to the moment someone else realizes the same thing (except of course that these realizations can only happen after the thing happened).
In relationships, what counts is the memory and the awareness of shared experiences, knowledge, and interaction. Since you know that your friends and family members are individuals with a similar brain, you can reasonably assume that they experience similar perceptions as you do. Your familiarity with their way of reasoning (even if it differs from your own) enables you to "simulate" and thereby anticipate their reactions to the events that you both experience, and this is what creates the notion of a shared "now". When you're not currently interacting, the question of whether something happened simultaneously loses much of its relevance, and the shared "now" becomes much more blurred to something like "today" or "this year".