Bit confused...you're asking if you should be upset that your boyfriend is hitting on your friends. But your post had to do with an entirely different message:
" I was with M and H was with J, a potential new girlfriend for him. We all had a nice time. But yesterday, I was at lunch with M, and he told me he'd been chatting J up online, flirting with her. It blew me out of the water. Firstly, because I was horribly jealous. Secondly, it seems disrespectful of H to flirt with his potential gf."
Again, confused. Why are you jealous that M is flirting with J, if it's a potential girlfriend and it's a double date? Also, what was that about it being disrespectful of H? Came totally out of the blue. No reference to him flirting with J....
Can you clarify your situation?