What does marrying you or staying the night have to do with her being in love with you? It sounds like she is, and that's what matters. If her responsibilities dictate her schedule, that's not a knock against her. Those things change anyway, as time goes on. (Meaning her kids will grow and not need their mom around all the time.)
Her religious father preventing her from remarrying doesn't make much sense to me. If anything, a highly traditional guy would want to see her remarried and the kids being raised with the help of a responsible father figure even if he comes in the form of a stepfather because their biological father is gone. I'm not saying I think that way, I'm just saying that's how I would expect a typical "religious old guy" would view the situation.
Give it time. To answer your question, no. You build love with compromise and understanding.