But if she truly loved the husband, he wasn't her first.
If the potential White Court vamp is in love with the first person they sleep with, it can kill the inner vamp and leave them human. It's what both Thomas and Harry hoped would happen with Inara, back in
Blood Rites. So Lara couldn't have been in love with the first person she slept with; if that were true, she wouldn't be White Court. She might have fallen in love with someone else afterwards, but by then it would be too late to be anything other than a vampire.