Certified GKH Gardening Expert
Moonflower is a common name used for a few plant species, but the most common is Ipomoea alba, a morning glory species, so I will assume that is what you have.
Sometimes flowers will lose their scent after they are rained on, but should develop a scent again soon. Also check the image at this site to make sure the plant you have really is Ipomoea alba, because ther flowers sold as moonflower may not have a scent:
The flowers should develop small pods after they wilt, which will eventually turn brown. If none appear, there may be a pollination problem.