I don't think he'll be mad at her or he'll make a scene for this
First of all, I don't think it's his right, Elena didn't do it as a tantrum but bc she was suffering so much without him, it'd be rude of Damon to bitch her about this
But I'm sure he won't anyway, he'll understand her reasons and luckily even understand the deep love behind them, I'm positive about it
That be said, of course it won't be easy for him, he'll probbaly be sad and hurt not for the action itsefl, more about the fact she doesn't remember the good things they shared together or the love for each other and if she won't be resentful and hating on him, she won't be so nice neither more than probably
