This are relations of partial, deficient Duality. Both partners are able to support each other's “Suggestive” function, passing the information from their “Leading” function as Duals do. But their “Creative” function doesn't not pass the right information to the “Anticipated” function of another partner (as it would have happened with a Dual). That's where the interest to one another grows and admiration begins.
Semi-Dual partners are genuinely interested in each other. Semi-Duals usually have many topics for conversation and these conversations do not seem to be boring.
Although not able to directly “hit” each other's “Vulnerable” function, they both expect the activity from the aspect that is in the “Vulnerable” position of the partner and are unable to get it. That's where the mutual reproaches arise.
Sharing only half of the values, both partners expect the aspect of the “Leading” function to be passed in a different way (as it would be in Duality relations). That leads to the differences in the attitudes and ground rules.