I'm a Lactation Nurse, and I see lactation as a way to feed infants and small children. I've breastfed my own children for a long time, some of them for years. My Man and I were able to maturely blend the dichotomy of breast as both sexual plaything AND (it's most important purpose) gland which makes food and comfort and sleeping platform for infants pretty easily.
I never really cared for him to get my milk, it didn't do anything for me, he didn't seem to care either way, and I did wear a bra during sex for the first few months after each baby was born. but I leak like a sieve and would actually soak the bed if I didn't have a bra and several nursing pads on.
The dual use of the female breast CAN be successfully integrated into a healthy sexual relationship, as long as the understanding that breasts are FOR feeding babies and any other use is SECONDARY and not essential, is accepted.
I take a pretty utilitarian view of lactation, and it doesn't turn me on in any way. Helping women lactate is what I do for a living, so I see it all the time, and I've experienced it for years in my own life and only see it as part of a parenting Lifestyle, and can't sexualize it in any way. But, everybody is different, I think as long as the sexual allure of the lactating breast doesn't crowd out it's actual purpose (feeding, calming and nurturing infants) then, what ever works for y'all.