Fasts are supposed to help us learn self restraint in atleast 3 desires.
O ye who believe! Fasting is prescribed to you as it was prescribed to those before you, that ye may (learn) self-restraint,- (2:183)
When we fast we do not indulge in any activity that would in anyway ignite or satisfy these desires.
Between iftar and suhur we can eat, drink and have sex (but no sex in itikaf).
Permitted to you, on the night of the fasts, is the approach to your wives. They are your garments and ye are their garments. Allah knoweth what ye used to do secretly among yourselves; but He turned to you and forgave you; so now associate with them, and seek what Allah Hath ordained for you, and eat and drink, until the white thread of dawn appear to you distinct from its black thread; then complete your fast Till the night appears; but do not associate with your wives while ye are in retreat in the mosques. Those are Limits (set by) Allah: Approach not nigh thereto. Thus doth Allah make clear His Signs to men: that they may learn self-restraint.(2:187)
If a couple is newly married, even a phone call might ignite sexual desires BUT if a couple is old, much physical contact might not ignite anything. It depends from couple to couple. The couple should talk and set boundaries during fast.
The idea here is not "if hugging is permitted" rather it is "if hugging ignites sexual desires to nullify the fast"
Sometimes the effect of certain gestures (like hugging) might not be known to the couple, so I advise not to involve in them so as to keep the fast intact.