The 24-year-old world No 6 from Tokyo revealed hidden heartbreak to account for her surprise quarter-final defeat in the Direct Line Insurance Championship at Eastbourne by the unseeded American Chanda Rubin.
Date, the top seed, crumbled 6-3, 6-0 then disclosed her mental anguish over lurid love allegations published in a Japanese magazine.
The story suggested that her surprise arrival in the semi-finals of the French Open was due to an affair with her coach, Kadru Maruyama.
"That hurt me deep inside," said Date, the only player among the world top 10 in the singles at Eastbourne. "The writer of that article bothered me and now I'm unstable mentally. There was no truth whatsoever in what he wrote. But it has affected my working relationship with my coach.
"Because of this gossip, I am not as disappointed about going out of the tournament as you may think. I just couldn't get into it."
Date believes she will be unable to recover her composure before facing Belgium's Sabine Appelmans in the first round at Wimbledon next week.
Date is known as the sleeping beauty to friends because one of her favourite pastimes is catching 40 winks. And she has shunned sightseeing, staying in her hotel room for fear of restarting the rumours.
At times she looked half asleep against 19-year-old Rubin, who reeled off winner after winner with sliced forehand drop-shots. Date did not even move as Rubin smashed an ace to clinch her place in the semi-finals.
There she will meet another unseeded player, Germany's Christina Singer, who defeated Yayuk Basuki 6-4 6-4. The other semi-final will be between Natasha Zvereva, of Belarus and Nathalie Tauziat, of France, who defeated Lori McNeil.Reuse content