Faith and Choices

[Raynor]

it doesn't preclude him feeling regret - either as a Captain might regret having to be harsh on the keen young hero

Well, being harsh was not the cause of his regret, as he stated. That a soldier would develop positive feelings for his commander, is a cause for contentedness, especially since reciprocating would not interfere with anything else Aragorn might be personally involved in. It would be something he would want to cultivate. While Eowyn could indeed love Aragorn both as man and as a captain, the more the latter is prevalent, the more it would deduct from the substance of their drama, in which they interact as man and woman, not captain and soldier. While the inner workings of her love, her projections, are closer to your idea, she still relates to him as a desired lover.