Kate Gosselin's Ex-BF -- She Only Wanted Me For Ratings

Kate Gosselin's ex-bf Jeff Prescott says the mother of 8 only wants to date him to boost ratings for her show.

Sources close to the millionaire COO tell TMZ Jeff THOUGHT he was in a real relationship with Kate, but quickly learned she only wanted him to appear on "Kate Plus 8" this season as her love interest.

We're told Jeff agreed to do the show a few months back, but when he realized what was up, he bailed because he felt she was just using him. No shock ... they're not on speaking terms.

So much for a new babysitter ...