Borrowing something from the bachelor/bachelorette topic...
Those little flowers on the dialogue box, on the left side. They'll be colored if they're an available marriage candidate for you, with the exception of Sage, Michael, Ariella, and Dirka.
When only one of the flowers is blooming, the flower will be that white/pale blue color (like in the image; the person who took it was probably playing as a boy). When you gain another, both will be purple, and when there are 3 on display they will be a darker blue, and so on. However, when the flowers turn pink, there will be five blooming and a larger bud at the top; for the final heart level, all the flowers will have bloomed and they will be red, with a large red flower at top.
And yeah, kinda bored right now. I'm waiting for fabric paint to dry, so forum browsing while I wait it is...