It is wrong and harmful to compare what Allah (SWT) has given us with others. Comparing with others can make us less appreciative to the bounty of Allah on us, and even under estimating the bounty and ungrateful to Allah (SWT). Comparing with others make us lose the real taste of the bounty. Prophetic advice to Abu Thar: Never look in worldly matters to those who have more than you, as that can make you disrespect the bounty of Allah on you.
If your fiancée compare you with other men, will you like that?
We need to thank Allah (SWT) for every bounty He granted us and never look at others.