I'm trying to remember way back when we had bettas spawn...I think a lot more floating/tall plants are needed. What kind of filtration do you have? I can't tell but you want a slow gentle flow that won't disturb the bubble nest, like a sponge w/ very slow air pump setting. Temp? I "think" ~80F is good, look it up!
Your pic is funny, looks like the male is above the rim let alone the water level. Is he jumping for joy, lol? Sorry, couldn't help it. What is the white net thing in the left half?