Can they sense each other??? Bettas?

I have a male and female betta in a 5 gallon tank and a non see through divider between them. They are both fed betta pellets for breakfast and a few freeze dried bloodworms for a evening snack.They both keep going to the divider and ramming at it. The male has made a huge bubble nest and the female is swollen I assume with eggs and the white pimple is there where the eggs will come out. Do they smell each other or perhaps sense the other ones presents???? The male never made a bubble nest til I added the female but he has never seen her.