My best friend makes strange comments and gestures about my boyfriend and I don't know if I should say something or not?

We have been friends for 20 years and she’s never acted strange or made strange comments towards any man I’ve dated. My boyfriend now, who I very much think is the one, and we’re expecting our first child, she makes some odd comments sometimes. Quite a few years ago when I showed her a picture of him and said “do you think he’s cute” she said not really no. Then when she met him in person she said “wow…he’s a lot cuter in person”. Then she made a comment the one day how she wishes she could have the type of relationship me and him have. Never thought anything of those comments until she started physically acting weird around him. She was over our house and I went downstairs to do laundry and she went to my bedroom where he was and sat on the bed and asked him what he was doing. He was very obviously playing a video game but she kept inching closer to him so he said well I’m gonna go help with laundry and came downstairs and told me. I just shrugged it off and figured she didn’t mean anything by it but he said it made him very uncomfortable. Then at our gender reveal party she cornered him in the kitchen and fixed his chain because the clasp was showing and was touching his neck to which he said I can fix it myself and then walked away. She’s also been very distant with me since we started dating years ago and even more since I’m pregnant. She stayed at the gender reveal party for about an hour then left. I texted her and said thanks for coming and she said “of course. It was nice to meet his parents” it was just a strange response considering she said nothing about the gender of our child. I don't know. We are both just weirded out by this. I also want to add she was diagnosed with bipolar disorder and hasn’t been herself since.
My best friend makes strange comments and gestures about my boyfriend and I don't know if I should say something or not?
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