Playing or aggression?

I have two cats one male and the other female. I’ve had them for 2 years and both are fixed. I’m trying to figure out if they are playing or fighting. The male cat is bigger and more dominant and the girl cat is more playful and cuddly. They both chase each other and will take turns who initiates. Today I noticed the male cat was pouncing on the female and they were making noises but she wasn’t fighting back much. I just witnessed the boy cat bite her and take some fur with him! I’ve never seen him do that before and I’m getting nervous! I’m 37 weeks pregnant and this isn’t typical behavior. Are they still playing or would you consider this fighting? Any suggestions? I can’t really separate them and when I’ve had to in the past they both sit at the door each of them on opposite sides kinda waiting to be able to see each other.

The male cat also occasionally goes after the female when she’s done with the litter box. He doesn’t do it much anymore since we added a third litter box and have been trying to correct this behavior. I just don’t want to see my girl get hurt! This worries me since I’m about to have a baby too!

Any advice would be great! Thank you!