it could be a boy placket, they get even the best of us somtimes with their,, am i a boy or a girl looks,, you could try a different female,, theere could be other things too,,, most bettas arent spawnable if they are more than a year old,, maby two at the most if she was a pet store find you really have no idea how old the fish is. and secondly some fish just dont like each other and wont spawn at all. to hopefully have a sucessful spawn the male needs a really good nest,, not just a few bubbles but a good size or the female wont like it and will refuse,, they both have to be conditioned well,, lots of protine rich food for a few weeks, not have the tank in a busy area or where it could get bumped,,, or tapped on the glass but someone. the male is in the tank first then after he makes a nest put the female in the chiminy wait till she gets bared up top to bottom ,, not frount to back,,,and she is fat and full of eggs and her little ovisposert is sticking out then let them out and it may take a few days to spawn ,, but remove her if they are doing too much damage to each other.........are you ready for the 200 pluss fry that could result? they will need to be seperated by about 8 to 10 weeks old,, each in its own jar,,how are you going to keep the jars warm then? do you have baby fry food? what are you going to feed them? can you feed them at least 3 times a day?what size tank are you using as a spawn tank 20 us gal is the smallest i would go bigger is better,, what are you going to do with all the babies?? sell them give them away,, ???or can you keep 200 pluss babies if you cant get ride of them???do you have the space needed to do this,, can you devote about 2 to 4 hours a day to just doing water changes??
there is a ton more work than most people think revovling with breeding, and even the most experenced people can still have problems, so its not somthing to just jump in to even if you have read up on the subject.