In Italian the verb ‘fornire’ means to supply, which is similar to the French ‘fournir’. Both words seem to have their origins in Latin, seeing as one word in Latin which means the same is ‘orno’.
Then one could compare both the French and Italian to the English verb ‘furnish’, which in one of its meanings means something similar to supply. However, at some time in the past, for some inexplicable reason, English took the word ‘furniture’ under its wing. This word does not mean anything similar to the Italian or French verbs and even the Italian and French equivalents to ‘furniture’ are very different.

Stop reading, start speaking
Stop translating in your head and start speaking Italian for real with the only audio course that prompt you to speak.
I would love to know just how this transformation in meaning actually took place. One could suppose that the English version came about as a result of some misunderstanding arising from a conversation that took place many moons ago between either a French or Italian furniture supplier and an Englishman working in the same trade.
Whatever went on, the word ‘furniture’ came to be the collective term for all those items found in a building, and meant that future generations of French and Italians would be puzzled as to why a friend has become false.
Etymology is quite intriguing, don’t you think?