Today, I gotreceived a flier aboutfor rental friends.

It saidoffered for you canto rent friends, but I wondered if the friends were literally friends.

I think friends arebecome friends out of concermmon interest, so they are not friends as farse ones can't be friends, as you pay for them; the relationship is limited.

In addition, I can't imagine the feeling of those whom works as a rental friends.

Pretty sure 'whom' is incorrect here. You can revise the sentence to '...he who works as a rental friend' but not '...him who works as a rental friend,' and that's how you can tell.

While they behave as a friend of athe client, do they think about and treat their client as theiractual friends?

I guess they don't, so I think. I find the idea of rental friends are weird and incomprehensible.