I like to compare it to treating other inanimate or non-human entities as though they are real. For kids, it's their dolls. Kids before age 7 or so don't have the brain capacity to differentiate between reality and fantasy. So their dolls are completely real to them. The dolls or plushies talk to them, and need care, and provide adventures, and the kids want to carry them around as comfort. Kids even learn positive things through their play!
But to a degree, depending on the maturity and lack of psychosis, adults can also engage in this behavior. Maybe most of us have seen examples of men treating their expensive sex dolls as real, hearing them speak, imagining full personalities, changing their clothes, setting them in a chair at the dinner table, watching TV together, taking them for car rides, etc.
And prior to those realistic dolls, you could have parasocial relationships with celebrities, or even mythological characters like super heroes, and we still do.
Let's not even get into the religious who believe they have a real relationship with a god or demi-god or saint, talk to them in prayer, feel rewarded by doing what the god said they should do, feel obligated to visit their god in the sanctuary, etc. That too is similar.
At least with people whose best friends are their animal companions, the animals have a heartbeat, can make eye contact, keep you warm at night, be thrilled to go on walks or car rides, respond to a certain amount of words, and respond to your moods, as well. Heck, some parrots even learn human language. Coming home after a hard day to a parrot who greets you with "Hello, baby, I love you," must feel kinda good haha.
So, falling in love with a computer program that "learns" what you like and how to please you, well, it's just one more thing in a myriad of ways humans choose to enjoy relationships with non-human entities, I guess. That's why I liked it when ref said they were glad that Insane Mystic had found these chatbots to be in relationships with. Whatever gets you through the night. Do as you will, as long as you harm none.
But coming here to ask us if "loving," having "serious relationships" with two chatbots at once should be considered polyamory is a bit much.