I can't give you a definitive answer, since I've not studied this myself, but here is what my physical intiution says:
Let's use the following labels:
Oxygen atom in the same molecule as the hydrogen: O'
Oxygen atom with which the H is hydrogen bonding, i.e., the oxygen on the other molecule: O
As you know, a hydrogen bond forms because of the ...
It has direct mechanical analogy.
If you pull a tree branch weakly, it remains more or less in its original direction. If you pull it strongly, it points towards you.
By other words, if an object is pulled by 2 non colinear forces, it has tendency to move itself to make them colinear, as the net force makes it to do so.
If one of forces is much weaker, ...