Especially if both Fi users are immature and have it programmed in them that their values are so right that they're unwilling to listen to another person's thoughts and opinions without vomiting up their own beliefs and spraying the other person w/ it.
I don't know if immature Fi-doms are like this, but I've talked to a lot of IxFPs and a lot of them tell me that when they were younger they were pretty adamant with their beliefs and refused to acknowledge what another person's view on the subject. I've also noticed that a lot of xNFPs say that their ideal choice for friends are other xNFPs. Is it easy to befriend each other because of your similarities or purely because you like seeing the same vigor in other people? * u *
But, basically, how do Fi users get along with one another? Let's say there are two super opinionated and sensitive INFPs that watch Boyz 'n the Hood together, and one of them finds the movie more insulting because of its portrayal of the hood and stereotypes of the urban black community, while the other thinks that it's a great movie because it gets the message of the cycle of violence and internal racism across, would they peacefully agree to disagree or start viewing their friend in a negative light because their interpretations go against each other's opinions in blaxploitation movies (these two are pretty simple so let's assume 70% of what they care about are blaxploitation films)?!?!?