Side 1: 2 dc in next st, 1 hdc in next st, 1 sc in each of the next 4 sts. The pattern works because the heart has more height from the bottom, which decreases as you go upward.
Corner 2: (2 hdc, ch 2, 2 hdc) in the next st.
Top Side: 1 hdc in each of the next 2 sts, 1 dc in next st, 1 dc into the center of the sc from Round 2 (spike st/long dc into the dip), 1 dc in next st, 1 hdc in each of the next 2 sts.
Corner 3: (2 hdc, ch 2, 2 hdc) in the next st.
Side 3: 1 sc in each of the next 4 sts, 1 hdc in next st, 2 dc in next st.
Corner 4: (2 tr, ch 2, 2 tr) in the next st.
Bottom Side (End): 1 dc in next st, 1 hdc in next st, 1 sc in the last st.
Join with a sl st into the first sc.
Note: You should now have 11 sts on each side between the ch-2 corner spaces.
Round 4 (Border)
Ch 2 (counts as first dc).
Dc in each st until you reach the corner space.
Corner: (2 dc, ch 2, 2 dc) in the ch-2 sp.
Sides: Dc in each of the 11 sts across the side.
Repeat the Corner and Side instructions around the square.
When you make the last side, dc in the remaining 5 sts.
Join with a sl st to the top of the beginning ch 2.
Note: You should now have 15 sts on each side between the corners.