Catherine Reynolds, 43, who has been in a relationship with Dr Michael Lever for three years, said she had no concerns about leaving him with her 13-year-old son.
She said Mr Lever lives with her in Ayr and that he has had a positive influence on her son.
Miss Reynolds gave evidence at the trial of Dr Lever, who is accused of assaulting Caroline Lever between March 1993 and January 2001 at properties at Dowanhill Street, Glasgow, and two other addresses.
Miss Reynolds and Mr Lever met in autumn 2010 and she met his children at Christmas that year, Glasgow Sheriff Court heard.
She said Mr Lever nows lives with her and her son, and her 20-year-old student daughter when she is home.
Solicitor advocate Tony McGlennan, defending, asked: "Has he ever been violent to you?" The witness replied: "Never." Dr Lever earlier denied the allegation that he pushed his wife on to a table and choked her while she was pregnant.
The trial continues.