They break the barrier more likely because they are trying to have more space to explore, or trying to escape the actual tank.
They are also more than likely only acting like that because of a breeding response, the males can get frustrated and the females can be more defensive when they are being bred/being exposed to males. Males should be cycled regularly so they don't exhaust themselves or refuse meals for too long, and ESPECIALLY should not be kept year round with a female...
They shouldn't be homed together in one tank, even with a barrier. Give them time to settle in separate tanks. Make sure they don't have each others' smell on them, and make sure they have proper hides...
And if you don't want to have to do snake abortions, you should probably make sure to practice snake birth control by keeping them apart. They will breed as long as they are kept together.