Will and spoiler: Sarah/Emily not being "in-sync" with each other was emphasized a lot during much of their relationship. spoiler: They became more "in-sync" with each other after their divorce.
Emily/Sarah is responsible for Will meeting Summer/Natasha, while Summer/Natasha is the reason Will is reunited with (and later married) Emily/Sarah. However, neither of them are involved in Will meeting April, whom he meets on his own before proposing to the former and meeting the latter.
When Will is telling the story, it's Maya who suddenly notices April, just as she (April) came into his life unexpectedly.
April's collection of copies of Jane Eyre with inscriptions in them. What if those books belong to people just like April? They might be searching everywhere for the book with their inscription in it because it means so much to them, but they'll never find it because April is hoarding them. Though maybe she plans on getting rid of them after she finds hers at the end.
