They are both natural. To make someone do something has an element of compulsion and forcefulness, perhaps against their inclination, whereas to get someone to do something is more a question of persuasion and negotiation.

Yes, I agree that either one will work. In my opinion, however, "make him understand" implies more of a frustration/anger with you really laboring at trying to "get him" to understand. Very, very subtle differences, but I visualize "making him understand" as more of an argument and "getting him to understand" as a softer conversation.

You would likely say (and write) "I am trying to make him understand how I'm feeling" but "I am trying to get my husband to understand how I'm feeling" is acceptable in spoken English as well.

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