First of all - relax! Rest assured that this is a good thing. Heís feeling happy and healthy and doing what comes naturally in the world of betta men! Heís hoping for dinner and a movie with a lovely female betta!
Please donít put a female betta in with him, of course, though - because their mating rituals can cause serious or permanent damage to both of them unless you are trained in breeding betta fish.
Donít worry, nothing bad happens without a night out on the town with a girl for your little betta guy. His bubblenest is just letting you to know that things are fine with him and heís feeling fine. Heís thanking you in his way for taking such great care of him!
If your betta is not blowing bubbles, then check all water conditions and aquarium conditions - his water temperature, pH, cleanliness, water conditioning, tank cleaning schedule, any drafts in the room, or harsh direct sunlight, or other disturbances to your little betta boy in his living environment.
With the perfect living conditions for a betta fish and the correct feeding specific to this wonderful fish, your betta fishy should make many a gorgeous bubblenest in his lifetime. ( :