What are red flags that my boyfriend is being harassed and stalked by girls I know?How can I get them to stop?

A boy I'll call Ilia* might be stalked and harassed by a girl I'll call Sara*. Ilia* just so happens to be my boyfriend and Sara* just so happens to be one of my "friends". When Ilia* and I go out, He almost ALWAYS wants me to kiss him on the lips, kiss him on the neck, or hug him for a really long time. A girl I'll call Julie* likes him too, but Julie* told me and leaves him alone, unlike Sara*. A girl I'll call Ashley*, who is also one of my friends, likes Ilia* too, but never told me and acts just like Sara*. Ashley* never used to act like Sara*. One time, Ilia* had a party and he invited Ashley*, a girl I'll call Kayla*, a girl I'll call Annie*, a boy I'll call Jet*, a girl I'll call Tatiyana* (she's his sister), and a few of Tatiyana's friends. Sara* just showed up out of nowhere. He asked Kayla*, but she said that she didn't invite Sara*. Julie* didn't go to the party because she didn't want to upset Ilia*. One time, Ilia*, Tatiyana*, and I were watching a movie together and it wasn't very sad, but he looked like he was about to cry about something else. When Tatiyana* and I asked him what was wrong, he said, "Nothing. I'm OK" and we acted like nothing ever happened. Tatiyana* knew that something was up. When Tatiyana* left us alone for a minute, Ilia* broke down and said, "Ashley* and Sara* won't leave me alone.Sara* called me and I don't know how she got my number. I only gave it to you". Tatiyana* came in a little bit later to see if everything was OK, but we didn't act like nothing ever happened. We told her the whole thing and she got really upset. It's gotten to the point where Julie* always wants to hang out with Ilai* and I. Are these red flags of his situation?