It is narrated from Hazrat Maymunah (may Allah be pleased with her) that a person asked the Prophet (peace and blessings be upon him) about this issue: If a man kisses his wife while both are fasting, what is the ruling? The Prophet (peace and blessings be upon him) said: "Their fast is broken."
Hadith Referenceمسند احمد / من مسند القبائل / 27625
Hadith Gradingحکم دارالسلام:إسناده ضعيف لجهالة أبى يزيد الضبي، وقد ثبت أنه ﷺ كان يقبل وهو صائم، انظر: 25613