That is normal behavior, a bit of nipping and chasing is all part of the courting behavior and this get her in the mood...she likes/needs it rough...lol.....and then once she submits and moves toward him usually head down- he will become gentle and slap her with his tail and swim in an "S" as to ask her to follow him to the nest and once under the nest often he hits her again and she runs off only to return head down..... the spawning act is gentle and awesome to watch and once it is over (1-6hr)..."bam" he hits her again.....one of the most interesting spawning acts I have seen
As long as the female is not panting and torn up really bad-I would not disturb and leave her with him-but you have to have some place for her to get out of his line of sight with either more plants or a cave or something,,,he will know she in in the tank but she needs to be able to get out of his line of site too.
Try to keep your hands out of the tank and disturb them as little as possible, let him decide where things go in the tank.
Good luck with your spawn....