I need advice

I’m 18 and my boyfriend 19. We’re both studying the same degree at the same university and spend a lot of time together as we share most our classes.

He stays in the student accommodations and I stay at home, he has a lot of other female friends and I have no problems with that, except one night he told me him and a friend stayed up together talking until 1 am in his room, I’ve met this girl she has a boyfriend but she gives me a feeling like I should be worried.

I trust my boyfriend so much but he brings her up in conversation sometimes and it just makes my blood boil. I want to ask him if anything has every happened between them because we have gone through a rough patch recently and I keep thinking about it and I’m not sure what to do.

I feel like if I ask it will come across like I dont trust him when I do but I’ve been cheated on twice before and I’ve realized how easily it happens...

What do I do?