All he would give her is vague "I have to do stuff for Mr. Wayne" which could just as well be bullshit for all she knew. And the one time she really got pissed about it she got over it and told Terry that she realizes he probably saw Bruce as a surrogate father figure and was more fogiving him after that. Also Epilogue (which is canon mind you) shows that they're still together long after high school with Terry on the verge of proposing to her and she stuck with him even knowing he was Batman as that episode showed.
You can't really buy that level of loyalty that's the comparison between Terry and Bruce. Bruce sacrificed his personal relationships and happiness to be a hero, Terry didn't.