“When Peter was almost thirteen, May met Carter.”
“Not too many months after Carter moved in, May got a promotion at work.”
When May gets a new boyfriend, Peter's okay. When Carter moves in, he can deal. When May gets a promotion so she works days and Carter works nights, Peter finds it harder to deal. When Carter starts abusing him, he begins to feel crushed by the weight of it all.
(The classic Peter whump fic where May gets a new boyfriend and he abuses Peter.)