For Milan this season will probably not have a happy ending and certainly not a comfortable one in the last three games. Even Lazio got lucky now that AC Milan failed to win again or otherwise they could have gotten into trouble as well. Now it seems that the first four ranks are almost certainly taken by the top four as per current standings in the table. I wouldn't expect any changes from here on and for AC Milan the next seven six days could be very ugly if they get eliminated from the Champions League and then Lazio perhaps win their game in the Serie A or even tie it, the dream to qualify for the biggest European club tournament will also slowly but surely come to an end.
Lazio's run of good fortune?
Do you mean the run consisting of three losses and one draw out of six games?
You could rather say that their run of good fortune was due to AC Milan and AS Roma having a bad run, but not because Lazio performed well. It is not about accepting bad fate for AC Milan, it is about accepting a very bad position from which they now have to try to make the impossible actually happen.
But I am sure their heads are now full with Champions League and not with any considerations about the Serie A results.