The relationship must be like talking to a brick wall...though somebody's probably already married one of those too.
But, in all seriousness, I can understand the appeal of "objectivum sexualis", or however it's spelled; you don't have to support it financially, it never talks, it can't leave you or cheat on you.
And if it's a wall or something similar, it can give you shade while you read or rest, leaning back on it, never having to worry about it moving. In a way, it's seductively peaceful and superior to a human.
I can imagine that, when I'm retired, I'll have a favorite spot like, say, a tree or a chair, that I can always count on when I'm doing old people stuff like reading and sleeping.
That's just my angle; the people who actually have this mental disorder may see it totally different, but to me, it's not as alien as one might think.