How do I (26 f) make sure I don’t cross any boundaries with my roommate (25 f) and her boyfriend (28 m)?

Hi! Long time reader, first time poster. I’m just looking for a little advice as I am autistic and want to make sure I’m not reading any social cues wrong! My roommate is amazing, I lucked out so hard with the fb lottery, and everything has been great! However, whenever her boyfriend comes to visit, I get worried. I always see all these tik tok and instagram posts about the roommate or the ‘girl best friend’ who has terrible boundaries and is in love with the boyfriend, and it makes me worried that I am coming across that way and making my roommate uncomfortable. Boyfriend is a great guy, and he and my roommate are perfect for each other. But, my roomies boyfriend and I have a lot of similar interests, opinions and thoughts on moves, pop culture, music, etc. Is it coming across as pick me or bad when I engage in conversation about these things? I am demi sexual and have no interest in my roommates boyfriend, however, sometimes when I am talking to him, I get super excited and then I feel self conscious because I am worried I am coming off as if I am flirting. I love talking about my more niche interests with someone who is just as passionate as me, but the last thing I want to do is make anyone uncomfortable, especially my roommate or her partner. I want to be his friend, because he, like my roomies, is cool as hell, but I also don’t want to cross any lines. Anytime I engage in conversation, all of the posts I’ve seen before just flash up in my mind and I’m scared I’m gonna cross a boundary I didn’t know existed. I love my roommate and I want to renew a lease with her, so I’m coming here to make sure that