Third wheel advice?

I have been dating a super sweet, handsome boy for a year. He is incredibly kind to 2 of my close friends, but neither seem to understand that their constant third-wheeling is annoying. What should I do?

Details:
Boy and I are in the same lunch period. Its a sacred time, the only part of the day where I get to be with him. We are both in several AP classes and its a time to comfort each other from otherwise stressful days. Friend A sits with us every. single. day. She seems oblivious to the fact that we may want to be alone sometimes. It's awkward because I can't say things to him that are sweet because she sits right in front of us. She's been in relationships which is why I'm so confused.

Friend B is a mutual friend of ours. Sometimes we feel she intentionally separates us. If we are with our friends she will sit between us at the dinner table, or even in the middle seat in the back seat of a car between us.

I talk to both of these girls CONSTANTLY. I'm not avoiding them or paying them any less attention since I've dated this boy (it's also been a long time).

What do I do?