Well, seems to me that what happened with Andy and Tessa was, basically, just what happens to most fledgling meetups -- two people felt attracted to each other, then got to know each other better and found out that they weren't compatible enough for a long term relationship. I'm sure they'll both eventually find people with whom they are compatible.
Trouble is, Andy found that the show also gained him lots of publicity, and, for both good and bad reasons probably, this is important to him -- he loves limelight and people, I think (that's the way I interpret his over-the-top affection toward so many of the women, anyway); he believes in causes that he'd like to publicize; and he even has the job of Navy recruiter in a very tough time for the military. For all those reasons, I think he had a whole lot more invested in producing a show with an idyllic happy ending. So for him, the show -- and by extension the relationship -- meant a lot more than it did to Tessa, so he's having trouble giving it up.
All she's had to do is give up one of the many guys she'll be initially attracted to in her life but not want to continue with. That happens to most of us many times. He's having to give up that, plus a real opportunity to get his name and self and causes out there and prominent -- which he really really wants to do -- and that's a much bitterer pill to swallow, I'll bet (besides which an achiever like Andy is likely to see a relationship ending as a failure for somebody -- so you're going to blame yourself or be kind of angry with the other person, or both, I suppose.)