What does it mean when they have a plant with a broken heart next too it?

Sometimes they are looking right at one of my plants and sometimes just walking around.

I don't know if they are broken hearted because:
1) they cannot afford the plant
2) the plant is injured and they feel bad for the plant
3) I do not have a certain plant they are looking for
4) my nursery is just too beautiful to bear

I only recently started seeing this one.