I'm confused (vent?)

So, me and my girlfriend were in the bathroom at school just a minute ago, and she told me that she thinks she has a crush on my friend Oliver. We aren't close friends, but still friends. My girlfriend told me that next time I see Oliver, to hint at him, tell him "hey, I think (gf's name) wants to hang out more" and she wants me to ask if he has a partner. So, I don't know if she forgets that we're dating or if she just doesn't care. I also like this guy, but he has a boyfriend and I'm best friends with both of them. I feel bad because I don't wanna leave my girlfriend, but I feel like she doesn't care that much about the relationship as I do. I always try to keep her happy and make her smile. I also feel bad if I leave her because she recently lost her grandpa and I feel like a break-up will make her even more upset. I love her, I really do, but I feel like she doesn't love me anymore. So, I'm confused because I don't know if she loves me or not. Should I break up with her?