<human>: Could you distill the essence of the text into 1-3 sentences?

I have a friend who is smaller and thinner than me, who naturally also has smaller boobs than I do. We both have boyfriends who love us a lot, so you'd think we're fine. But she keeps mentioning how she's unhappy with her boobs, how she wished they were bigger, etc etc.

The first time she did this I was a bit surprised, but I told her 'at least you won't get a backache', 'at least they won't sag', that they look good in their own way and that she has nothing to worry about. 

However lately she's been mentioning it more often in front of me, and I don't know how to respond anymore. My boobs are bigger and they don't sag or hurt, so I just don't feel like lying anymore and coming up with ideas why my boobs aren't perfect. 

She even brought it up when her boyfriend was with her too, he told her himself 'I love them' but nope, still not satisfied. Sadly she doesn't see that she has a great ass, a pretty face and in general is really cute.

I'm out of ideas what to say next time she mentions it to me, it's clearly her own insecurity problem and if her boyfriend can't fix it, there's no way I can and I'm tired of lying to make her feel good. So what do I tell her?
<bot>: Insecure friend is jealous of my bigger boobs and keeps talking about it, I don't know how to respond anymore.