Your story sounds exactly the same as the one Alex and I went through nearly 18 months ago...
Alex is 6'1" was 60kgs when diagnosed which was already 10-15 kgs under his ideal weight and he dropped to 48kgs before being hospitalised.
Like your husband, he complained that he just couldn't take any more food and he would try again tomorrow when he felt better. Like you, I bullied, let him go, cried, cajoled and tried reason. I even went so far as to accuse him of slow suicide and if that was what he was doing, could he please inform me now so I could leave and not watch him do it (my worst day and one which I am not proud of). I tell you this to demonstrate I know the frustration you are feeling.
My Alex could not tolerate TwoCal and literally 3 sips into a can, he felt unwell, complained of bloating and the 4th sip caused him to bring it back up. Actual food was not an option due to difficulties with all of the above plus swallowing issues and pain.
This all happened during induction chemo, and the oncologist refused to treat any further until he gained weight. TwoCal made Alex sick so he was put on a pump which ran 8-10 hours overnight with a product called Nutrison. He was hospitalised at first as his weight was so low, they were concerned with "refeeding syndrome" which is a condition where the body can't cope with the return to normal nutrition and can cause life threatening events such as heart attack.
In hospital, he learned how to use the pump and gained 5kgs in 5 days. He took 2000 cal per day this way and whilst his weight never recovered to anywhere near normal, he gained 10kgs and stayed there all through radiation. I learned how to work the pump as well but my help was never needed. Alex used the pump for the next 12 months at home and became so adept at changing the bags over in the middle of the night, there were occasions when I would poke him awake, believing he had turned off the alarm on the machine and not changed the bag.
There appeared to be two issues: one was nausea and vomiting if pushed; and the other was bloating where Alex felt extremely uncomfortable after 3 "mouthfuls" where the 4th would cause him to throw up. This also happened when PEG feeding so was not a psychological or gag reflex. The radiation oncologist led me to believe that Alex's issues were unusual and something to do with Alex's attitude (hence my extremely inappropriate outburst). The oncologist believed that it was a matter of drive or will power. The oncologist was wrong!
My advice: Find someone who will listen to the issues without judging and then attempt to solve the problems. We ended up with slower feeds via pump overnight (needed to be changed after 4 or 5 hours unfortunately), medication for reflux (Somac) and an antinausea med (Maxalon)to help get the stomach contents moving which I believed was Alex's major problem although have no idea why his treatment would cause this.
Your husband is not abnormal and don't let any healthcare professional convince you otherwise. He is probably feeling just as scared and frustrated with his inability to eat as you are.
Please feel free to PM me with a phone number if you need more guidance or information, and I will call you at your convenience.
Karen
Love of Life to Alex T4N2M0 SCC Tonsil, BOT, R lymph nodes
Dx March 2010 51yrs. Unresectable. HPV+ve
Tx Chemo x 3+1 cycles(cisplatin,docetaxel,5FU)- complete May 31
Chemoradiation (IMRTx35 + weekly cisplatin)
Finish Aug 27
Return to work 2 years on
3 years out Aug 27 2013 NED

Still underweight