It shouldn't bother you because you should have multiple other Women and she's only a "plate" however I get it, the male ego doesn't like when the hot chick he's fvcking is looking at another man with lust. So, what you need to do is treat her like a little slut in bed. I'm not kidding, you need to get her legs shaking, make her squirt with explosive orgasms, etc. You may THINK this is to blow her mind and make her feel like "OMG" he's so good at fvcking me" No, this is for her to think about YOU fvcking other Women like that. Women are very competitive with each other and they do not like to think about the Man that fvcks her very good, doing it to another Woman. (Unless she's into that Cuckquean lifestyle but that's another story). You want to make her feel like she needs to keep an eye on you instead of you keeping eyes on her.
Overall, like i said, you can't stop her from checking out other Men because she's just a hot chick you're casually hooking up with. Even if she was your Girlfriend or Wife, she'll still look at attractive Men just like us Men still look at attractive Women even if we have a Girlfriend or Wife. I have been the guy many Women look over at while they're with another dude and many times it's just eye candy to her and nothing more.
I'll also add, You need to become a Man that can get multiple cute/hot Women if you choose to, that's your "Power Play". If she knows that and wants to wander off with someone else, let it be and fill her spot with another HB10. A Man with options is valued much much higher compared to a Woman with multiple options because D*ck is thrown at Women every day. It's not that common for a Man to just go and get HB8+'s when he wants to.
Also, If she's a plate... push the kinky limits with her, Tell her you want to fvck her in the ass, tell her you want to have a threesome with her, tell her you jerked off to a picture of her and one of her hot friends lol. I've said things like this to many Women and their initial reaction is "OMG i can't believe you said that" or "You're freakin crazy" but guess what....... their yappin their lips doesnt mean anything if it STILL got their pvssy wet. Women are strange like that, they will verbally say one thing but yet they're getting wet. Have fun with it and don't get hung up on little sh*t. I've been there along with many other guys on this forum and at the end of the day it's not worth stressing over. Just have fun with it.