You have the right ideas, basically, but there is some more work to get the statements into symbolic logic.
Let $L(x,y)$ be the relation "$x$ loves $y$". Then we get:
$$a.\quad ∀x \, ∃y \, L(x,y)$$
$$b.\quad ∃x \, ∀y \, L(x,y)$$
(The exact punctuation depends on the logical system.)