The 22-year-old daughter of Bob Geldof started dating the rocker in January.
And now Peaches is allegedly prepared to change her religion to move one step closer to walking down the aisle with Cohen.
A source told British newspaper The People: 'Peaches has a fondness for all things Jewish and in particular Jewish men. Last year she dated Jewish film director Eli Roth and after splitting with him in November she soon met Thomas.
'She is learning Hebrew and is ready to change her life for Thomas because she thinks he is the one.
'They have moved in together. They are completely committed to each other and now Peaches is just waiting for him to propose.'