Continuing with the post below

It is not like there were 10 persons living in that house and he mistakenly accounted for only 9 of them or even two persons sleeping in separate rooms. It was two persons sleeping in the same bed of the same room.

In addition entering a house through a bathroom makes the intruder more susceptible to being surprised unlike entering it through other rooms where it is less probable for an unoccupied room to become suddenly occupied.

I was also thinking that bathroom windows are often not large enough for a convenient entry by a human like regular windows especially when they are for a separate area like the one for the toilet in the bathroom here . I searched a little bit and found as shown in the windows picture from outside HERE in addition to that, the bathroom windows were not even on the first floor. On the other hand it seems that there are windows that are easier for breaking in below.

Back to the issue of size, if we assume it is the other big one, why would an intruder choose to trap himself in the toilet area and close the door? 

Remember, all that in a house described in the caption below the picture in #5 HERE as being in a "gated community with high walls and 24-hour guards".   

Also, moving without the prosthetic legs fits better with expecting being the shooting attacker than the one being attacked or shot at. One could think that the first thing a person with such disability especially if it was also a reason behind his fear would try in such situation is to handle the issue of his mobility. Instead what we see here is sacrificing mobility in order to reach the target faster. In other words we see here sacrificing faster reaction later because of lower mobility capability for the sake of faster action at the beginning which fits less with expecting to be attacked by the target. On the other hand, it seems to fit much better with him trying to reach the victim, knowing it is his girlfriend, fast because of anger and/or intentionally trying to reach the victim while she is still in the toilet section of the bathroom.   

Also,why did not that sense of danger and urgency make the suspect try to awake his girlfriend fast by physically moving or shaking her? In addition to better preparation, she could in the mean time call for local security or the police and the like.