I would think, that although it being unsaid, it would be implied. Aragorn was protecting Frodo by not going with him. It would only be a matter of time that the Ring would beckon to him, and since he is a man, like Borommir, he might be influenced the first chance he was alone with Frodo. So really, in the movie he may be seen as 'leaving the fellowship' or 'letting frodo go', i think the book idea is he was doing what was best for the ringbearer, as all of them should have been doing whether they did it or not. Although he intended to follow frodo to mordor, when frodo wanted to go alone, he realized his doom to follow the ringbearer, just the few of them, and understood frodos descision for why he had to leave. (As given a great example by boromir)
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Yamaha G-245S History