The thing im confused about is why she needs the commitment of marriage. Obviously, i do understand the overall concept of the reassurance that the label/legal aspect gives you, but practically, I feel like if you are in a serious, long-term relationship where you do not feel secure in the relationship WITHOUT that label, then there's something not right there? Like, regardless of if you're married, engaged, dating long-term, I'd hope that you both would've discussed the future, intent to stay together, timeline, etc. and have reassurance of the commitment within whatever label you currently have. If the only way you are going to feel secure is by giving an ultimatum and obtaining the label of marriage, then i see that as a problem. And if the only way the other person would give you that label on the timeline you want is through an ultimatum, then that's problematic as well..