Fe = emotional expression, giving/receiving of it.
Fi = d33p feelings
Te = thought expression, producing/understanding
Ti = d33p thought structure
(let's not argue those defintions ok? I'm just using them to futher my clarification)
If a Fi type needs to express is feelings, he/she must go through Fe. That's why a Fe HA type can seem to respon well to an ExFp: being an extravert, the ExFp will feed the HA irregardless of the fact that he, personally, has a Fi preference. What counts is the external manifestation.
Same for Ti/Te. A Ti type needs to express his thought structure via Te, otherwise it's called autism. ExTps can look Te because of this: the content of the thought can be absolutely similar even if the underlying structure is absolutely different. This feeling is strenghtened if the Ti model is correspondant to reality, which, theorethically, should most of the times happen for ExTps, since it's modeled by extraverted functions.
So what do we get from this? That going narrowing down the defintions in order to always excavate till the essence can sometimes be absolutely fruitless.
Case in point, final example. Interaction between IxFj and ExTp. Both parties can, at first, sustain Fe and Te. In IxFjs case, Fe is used in order to build a precarious relational castle of warmth with the ExTp. In the ExTp case, Te is used in order to consciously adapt his behaviour to dating society's expectations, which is what an IxFj awaits. What happens then? The IxFj feels like there is no need for further warmth, since the relationship is estabilished. The ExTp feels there is no need for further formalities, since the warmth is estabilished. Therefore, the castle BOOOOMS simultaneously. Either the couple dismantles, or both parties keep up with a forced relationship.