What is the ruling on one who deliberately breaks their fast in Ramadan, and is a similar expiation incumbent upon them as upon one who has sexual intercourse with their spouse during a Ramadan day?

Fatwa (definition) Summary:

If the disbeliever is not hostile, it is permissible to treat them kindly, feed them, give charity to them, and supplicate for their guidance.

Detailed Text:

There is no objection to feeding non-hostile disbelievers, giving charity to them, and supplicating for their guidance. Allah Almighty said: {Allah does not forbid you from those who do not fight you because of religion and do not expel you from your homes - from being righteous toward them and acting justly toward them. Indeed, Allah loves those who act justly} [Al-Mumtahanah: 8].

Asma bint Abi Bakr (may Allah be pleased with them both) narrated: "My mother came to me while she was a polytheist during the period of the Quraysh, when they had a truce with the Messenger of Allah (peace be upon him) and their term (of truce) with her father. So I asked the Messenger of Allah (peace be upon him) for a fatwa, saying: 'O Messenger of Allah, my mother has come to me, and she is eager [or afraid, the narrator was doubtful], should I maintain ties with her?' He said: 'Yes, maintain ties with her.'" (Agreed upon upon).

This interaction must be accompanied by inviting to Allah Almighty with wisdom and good counsel, as Allah Almighty said: {Invite to the way of your Lord with wisdom and good instruction, and argue with them in a way that is best. Indeed, your Lord is most knowing of who has strayed from His way, and He is most knowing of who is [rightly] guided} [An-Nahl: 125].

However, it is not permissible under any circumstances to ally with disbelievers or take them as close associates instead of believers, as Allah Almighty said: {Let not believers take disbelievers as allies instead of believers. And whoever does that has nothing with Allah, except when taking precaution against them in prudence. And Allah warns you of Himself, and to Allah is the [final] destination} [Al-Imran: 28].

And Allah knows best.