Artistic nudes are their own genre, and there's also naturalism, which isn't a sexual lifestyle. Non nude depictions of breasts also usually aren't pornographic. There's a lot of room for tits in this world without involving porn. Breast feeding mothers sometimes feel empowered by sharing pics of themselves. There's the Breast Cancer campaign that celebrates breasts, I'd say that's non sexual.

There's even a movement that believes, rightly, that a woman should have every right as a man does to show off her bare chest if she wants to.

* edited for typos