She was snuggled up close to her husband.

Literal

She [topic-は] husband's side [to-に] snugly was-cuddling.

ぴったり寄り添う — ぴったり ('snugly/tightly') is a 擬態語 for close, seamless fit. 寄り添う ('to snuggle/nestle') is a compound verb — 寄る (approach) + 添う (accompany).