Main love triangle

I have just finished watching both series of 'Green Wing', which I enjoyed immensely. However, towards the end, I was increasingly getting frustrated by endless cryptic conversations between Caroline and Matt. I just did not buy the chemistry between these two at all. Possibly I just didn’t understand Mac’s character: it was very hard to perceive anything noble in him when he acted so aloof and condescending. I enjoyed the one-upmanship between Matt and Dr Secretan, but my question is: what did they all see in each other?