Husband isn't fasting ( Not fasting due to sickness, fever cough, medication) as he has medicines to take and he is having fever.
Basically making the other ejaculate for spouses is permissible according to this fatwa -in Arabic- on islamweb #122336.
Note that the major difference between wife making the husband ejaculate by her hand or more generally spouses making each or one of them ejaculate and masturbation is that a legal partner is -hopefully willingly- involved, which is not the case for masturbation. This is the used interpretation of (23:5-6):
And they who guard their private parts (5)
Except from their wives or those their right hands possess, for indeed, they will not be blamed - (6)
Which might be interpreted based on that as long as a legal partner (spouse/slave girl) is involved you are guarding your private parts -in a legal and halal way-, as else you might be involved in a haram act of zina of the eye (you might have seen a woman that you liked and masturbated) etc..
For example in the fatwa quoted above they presented this statement from al-Iqna' الإقناع -Hanbali source- (My own translation take it carefully):
وللزوج الاستمتاع بزوجته كل وقت على أي صفة كانت إذا كان في القبل،... وله الاستمناء بيدها
A husband has the right to seek pleasure with his wife at any time and in any way if it is from the front passage ... and he can ask her to make him ejaculate by her hand. (See for example here in al-Bahuti's commentary on al-Iqna')
Ibn Hajar al-Haythami -Shafi'i source- defined the act of "ejaculating by hand" -in His tuhfat al-Muhatj تحفة المحتاج - as follows (My own translation take it carefully):
وهو استخراج المني بغير جماع حراما كان كإخراج بيده أو مباحا كإخراجه بيد حليلته
It is forcing an ejaculation without intercourse, no matter if it was haram as if one did so by his own hand or allowed by the hand of a spouse (A more exact translation would be: a woman which is halal for him to have intercourse with)
This might also apply to fasting people for optional fasts, but not for the case of obligatory fast like in Ramadan.
As here the matter is as follows if the wife ejaculates her fast would be broken, so if the husband asks her to do so he might be involved in a sinful act. Therefore it can be considered as not permissible to seek pleasure with her nor to ask her to make him ejaculate or at least an act which one should avoid due to the sinfulness of invalidating an ordered fast.
'Ala' ad-Dyn al-Mirdawi علاء الدين المرداوي (Hanbali scholar) said in al-Insaaf الإنصاف:
(وله الاستمتاع بها) يعني: على أي صفة كانت، إذا كان في القبل ...
قوله: (ما لم يشغلها عن الفرائض، من غير إضرار بها)، بلا نزاع ... (And he is allowed to seek pleasure with her) means: in any way it was, if it was from her front passage ...
(as long as he didn't disturb her from an obligatory act without harming her) without any dispute.
This explains why one is not allowed to ask his wife which is performing an obligatory fast like in Ramadan or making up days of Ramadan (while the next Ramadan is too close for her to have the opportunity to make this day up another day) to give him pleasure or making him ejaculate by her hand or more.
See also this fatwa on islamweb #371503