Bee, it makes complete sense that your friend is saddened and frustrated by her SO’s behavior. And, I agree with other bees that it’s time to have a level-headed, serious discussion about this. Thus far, your friend has been waiting for her SO to prioritize their engagement/marriage and he has not proposed. However, from your post, I’m not hearing that she has a full understanding of his feelings and beliefs about their marriage beyond questioning why it’s a “rush.” Further, your post doesn’t indicate so, but I’m wondering if he truly knows how she feels and what her plans are. Communication is needed badly, or at least that’s what it appears to me. Your friend is, understandably, burnt out and questioning whether or not she should leave. And, please encourage your friend to mindfully examine that urge to walk (e.g., where is it coming from? Lack of love or fear that he doesn’t want marriage? Fear that fertility will begin to decrease and it will be too late to have as many children as she wants, or any at all? etc.).
Once she has done that without him, I’d encourage her to sit him down and calmly describe the facts first. For example, “I know we’ve discussed our future together several times, and I was thinking more about it. I am 29, we’ve been together for 4.5 years and we have built a life together in this home.” Now, emotions and opinions. This is where that first step (mindful examination) comes in. So for example, in one conversation I had with my SO, I said something like, “I respected your goal to buy a house prior to asking me to marry you, and was grateful that I had a partner who prioritized our future family’s security. And at the same time, I am now 32 and I’m beginning to get anxious that if we don’t move forward soon, we may have issues conceiving. I love you and want very badly to make a family with you.” Make sure your friend owns her feelings. No judgments or assumptions (e.g., “You don’t care at all whether we get married or not.”).
Also, this where I part from other bees: I don’t believe that ultimatums and demands have a place in committed relationships. I’m going to go ahead and make the assumption that your friend does not want him to propose out of feeling duress to do so, but out of love and a genuine desire to be husband and wife. So instead, say, “I’m beginning to wonder if marriage is something you want, or if you’d just be going through the motions for me” or “you’ve told me you will propose next year, and I find myself wondering why you would delay when we love each other deeply and want a life together.”
Be simultaneously direct and gentle. “You’ve heard what I want for my future; I need to know what you want.” If he dodges, bring his awareness to that: “I asked you x and you responded with y, which really didn’t answer my question.” Be a broken record; just keep gently reiterating your question. If your friend remains nonjudgmental, calm, and direct, she will likely get a better sense of what is going on for him through a conversation like this. If he says that he hasn’t wanted to tell her but he never wanted to get married, or something like that and is unwilling to shift, her way forward is pretty clear.
The very best of luck to your friend!