I do not have personal experience (as in, I have not done it, but know people who have) but if you try looking for secondary lactation, re-lactation, or adult breastfeeding, you may find a lot of different angles to it.
Re-lactation is a thing that requires a fairly constant and extreme discipline of body and mind, involving massage, hormone ingestion via cream or tablet, pumping, suckling, scheduling, etc. It's the same whether it's for a baby, a cancer patient, or a lover, as far as a body is concerned. Taking it to a part time situation is almost impossible - it is a lifestyle choice - whether suckled or pumped, the milk must be expressed or there will be discomfort, possible infection, and eventually a diminished and dry supply.
The women (I can't speak to the male side of it) I know who have done it have been involved in long term relationships, or have maintained it as a kink sideline. One woman had a husband dying of cancer - it was a gift, of her body, of nourishment that sustained his body through the end, and of her love. One woman maintained her milk supply after weaning her children and gained great pleasure from having her lovers suckle at her breast, as it is an intense bonding and physical experience - the same chemicals are triggered in the brain - intense chemical reactions - in a mother/child situation, it may or may not feel more or less sexual, and the same is true for adults. I do know women who have orgasmed while breastfeeding their children. For some, this carries intense shame, and for some, it is just part of the journey. That is not about sexualizing your infant, but purely about a body response.
I think there may be people who take it to a farm animal place, but frankly, most of the people I've known who have done, or still do it, are pretty vanilla looking on the street. you'd never know there was a nursing bra under that dress, but you might notice some great boobs!
zara