Bhai.
You should understand why u been called for Yemen missions.
1) Gulf countries funded you heavily on defence procurement and helps you in you bad times like since you born in 1947. Population wise we Asians fuk too much and reproduction rate is higher than these guys or any guys on this planet except Chinese
They called you because the commitment you gave to them. Man power is more in Pakistan when compared to them. Not only that you have strengthen you defence forces too. But think of it When your friends backtrack from backing you when you need them most. You don't get involved in Yemen crisis because sectarian violence will ripoff you armed forces into two. War of sunni Shia will divide your country itself.
Even if you don't go for them some one like Egypt or even US will. That's my point. Their frustration is because they think you back tracked from your words you gave them. Am not a expert in this field I will wait for Pakistani experts who can explain you in greater detail