Is the heir to the house, Elaine?
If she is an heiress then she can stay at home, but if the house belongs to MC, MC can do whatever he wants about it.
Legally Elaine would be allowed to stay in the house until the final will reading is complete. As common-law spouse she has far more legal rights and protection than a non-dependant child does. This is something far too many people commenting here fail to remember (regardless of their damn countries laws), the MC is over 18, he is not a dependant therefore a legal adult and Donald doesn't have to leave jack shit to him (why many wills, especially in the States are contested). He has no legal rights at all, however, he could quite rightly contest any will excluding him but, that's a whole other ball-game and debate and his chances are not guaranteed lol.
In-game...she gets the house anyway yes...providing she meets her conditions. Again, legally, as Donald's common-law spouse, she would get it automatically until a will reading. There is no plot-hole here or 'porn logic' for what happened in the story. All perfectly feasible.