I'm glad you feel that way. They're an odd couple in some ways, but on the whole, I agree that they mesh well. The key things are that they respect each other and they're attracted to each other. The rest is just noise.
Toby is an easy-going, pleasant guy who can get along with just about anybody. (Even Ulf.) Kira is NOT easy-going or pleasant, but the main thing with her is that absolutely demands that you treat her with respect, and as long as you do that, you won't have any real problems with her --- her egomania might be a little annoying at times, but it's nothing you can't live with. It also helps that Kira and Toby are both competent at their jobs. Kira is a powerful wizard, and Toby respects that. Toby is a valiant knight, and Kira respects that. They'll always clash in a few minor ways, and they'll disagree on things now and then, but as long as that mutual respect is present, their relationship will be fine.