As Kiarra said, if there appear to be eggs in the nest, the female has gotten much slimmer, etc. than she probably dropped. Another way to know would be to ask if the male had embraced her yet; if she came up to the bubble nest, inspected it approvingly, and the male wrapped himself around her and squeezed, she probably released eggs. Usually the female will float looking almost paralzyed for a bit afterwords.
However, if they are just chasing one another around, this could be a serious problem; the female may not be ready or may have rejected the nest. They should be split up ASAP if eggs were not released yet.
