Hi Daniel,
I'm seeing lots of blown highlights. I'm not sure if it's from the flash or your PP, so first question is, what PP have you applied?
My suspicion is that with (what I'm seeing as) the blown highlights, you've used the 430 on full power, or near enough, but you're describing these shots as having used it as "fill" flash. The purpose of fill flash is to provide a little bit extra - some kick, some extra light, if you will - but it's not to be your primary light source ....
With something like the 430 on full, it assumes the role of being the primary light source rather than a fill ...
And, absent any
modifiers (which will be typical usage when mounted on your hotshoe) this will also render some pretty harsh lighting.
Second question relates to your specific camera settings for these: you had auto wb set, didn't you?

The wb in the last image is way out. Look at the gentleman's shirt: the whites are blue. Look at the lady's skin hue: it too is blue. As is his.
Which brings me to the third concept I'll explore with you: this was a difficult ask: she's white and pale, he's dark and, well, black! Your camera's metering system is toast in a situation like this: do you meter against him, or do you meter against her? Bearing in mind that your meter works off reflected light, you can see that each of these subjects will reflect, into your metering system, different values from each of these people.
Which is correct? Neither, and both.

I raise this issue so that you can think about it a little, before we get down to some answers. Perhaps others may choose to add their thoughts? That can hopefully add much value to the knowledge base that you're about to acquire.
