Yes. Mary's interest was pretty made clear at the end of the run of Ordway's Power of Shazam title.
Of course since then the only actual interaction the two have shared as a "couple" since that book was cancelled is him transforming her back from Evil Mary to Regular Mary at the end of Final Crisis. In fact, the whole start of Mary's disastrous Countdown storyline is predicated on the fact that Freddy has payed for Mary's hospital bills (because her parents apparently didn't exist according to the Countdown people) and then left her a short note telling her not to look for him (basically telling her to get lost). It was all downhill from there.