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What jumped out at me most from this letter was when LW described that she didn't want to be one of "those gals" who wonders where things are going, and that she is hesitant to give an ultimatum because it's "unattractive." I sympathize with her desire not to be "that woman" -- that demanding, shrewish woman who will drive men away with her desperate need for commitment and of course end up bitter and alone. It's easy to bend over backwards so as not to live up to this stereotype, and just as easy in the process to forget that you still have the right to express your feelings and desires, no matter how "unattractive" they are.
If LW wants a commitment, she doesn't have to hide it, though she doesn't have to offer an ultimatum either. If her boyfriend has encroached too much on her life for her comfort level given his reservations about serious relationships, it's okay for her to say so. Instead of worrying about being "that woman," LW should spend some time thinking about where her boundaries are and what she really needs from her boyfriend. Then, she can open up a thoughtful discussion with him; if he respects her feelings and is willing to talk things over, that seems to me like a step in the right direction.