My headcanon is that Eva and Jean met while they were pregnant and Eva pursued the friendship so she could have someone to borrow diapers from. There's no canon evidence for this at all, but it entertains me.
I'm not sure we can deduce anything from the fact that Peter doesn't communicate on-page with Steve and Jean, since it's implied that the time he doesn't spend in the Sad Cave he spends as a bit of a workaholic (Marco mentions 12-hour days and at least one conversation has him going in early to work).
I think in #51 Marco says he and Jake have been best friends 'since second grade', but eh, ghostwriter.