FL faces inner turmoil because she starts falling for a new man despite being with the ML

Any shows where the ML and FL are together (either before the start of the show or early on in the show), but then she starts falling for the SML who pursue hers. She feels incredibly guilty feeling like this because she loves the ML as well. She never cheats, but the ML finds out about her feelings and that causes problems for their relationship. In the end, she stays with the ML because she realizes she loves him more.