Yes, Microsoft Windows mouse or touchpad selection will automatically select word boundaries while selecting from left to right. However, after it does so, you can reverse back from right to left to fine tune the selection to the exact end character you want.

And yes, it also changes the start character you selected to be the start of the word when in word boundaries mode. If you really want to select from the middle of the word to the middle of the next (further) word, you have to select the start character from left to right to next word, immediately reverse, go forward again, and reverse back to the stop character you want. Easy, eh? ;-}

The above also apply if you start from right to left, in that case everything would be in reverse.