My best friend is having a crush on a coworker, she’s been with her bf for 7 years now, I don’t know if I should talk to her about this

I (21f) think my best friend (22f) is having a really hard crush on her coworker and she’s trying to not notice her own feelings, she’s been with her bf for a bit more than 7 years now. This is the first time this ever happened for as long as we’ve known each other, these days she’s always talking about this guy (29m) which is her coworker, he’s in love with her and has already told her about his feelings one night while they were out drinking after work alone. This of course is just my assumption but I think she’s crushing on him from the way she talks about him, you can see from her face that she’s about to fall in love with him but I’m concerned, I don’t know if I should even ask her about this and tell her that she’s obviosly falling in love with this guy, she has a bf with which she’s got one of the most loving and healthy relationship I’ve ever seen, he’s genuinely a great guy (working, caring, smart etc.) that’s been planning a life together with my friend (you know…a house together, maybe getting a dog, being parents in the future etc.). I don’t even know if I can ask her about her feelings or if I just need to watch what happens…