I think my boyfriend likes my sister or am I just crazy?

Here are the reasons i think he likes her
-Anytime she calls, he gets excited and answers the phone
-He smiles and stares at her ( when she’s talking)
-She has this old crappy car that she no longer uses bc she got a new one and everyone he sees her he asks her to buy it (he’s a car salesman). She says she doesn’t want to but i think he just uses it as an excuse to talk to her.
- Last Christmas we were having a get together at his apartment and she came over, and fancied his roommate so they were talking and my boyfriend got so upset. Like he was really mad. He even thought his roommate went to my sisters house to have sex but he just went to the store. He was tripping. He said it’sbc he didn’t want them getting close bc he doesn’t trust his roommate. my sister is a single mom and his roommate does questionable things asks is basically a loser so I don't know shoot this one.
-she has an accent and he is always mocking her (he does like to do different accents)

It just reminds me of when boys used to like you in grade school.
I think my boyfriend likes my sister or am I just crazy?
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