I mean, someone has to address the double standards here
It's very weird when people hold Maggie's reaction to Meredith dating Nathan against her, accusing her of being 'immature' or 'delusional'. All Maggie did was have a crush on Riggs, which is pretty common. She doesn't act on it, she doesn't stalk him or anything crazy like that. She has a crush on him and that's that. Meredith was aware of this. Meredith then proceeded to start dating Riggs. Maggie then told Meredith and Alex that she had asked Riggs out, Meredith had the opportunity to tell Maggie that he was in a relationship with her but instead of that she told her sister “Forget him. It’s really time to move on".
Meredith not only proceed to repeatedly lie to Maggie about the whole thing, but then tells Nathan things that Maggie told her in confidence and encourages him to play mind games with Maggie (e.g. have him ask Maggie on a date and let her down easy, then it's behave horribly on the date etc). Then Maggie finds out in a very public way that the two were dating. This happened days after her mother (who also spent months lying to her) died.
Watching it for the first time, I thought it was very clear that Maggie was never angry about the two being together, but rather she was angry that her sister lied to her for months. Its even more engrevious when you consider that Meredith already knew about Maggie's issues with people not being honest with her with her own parents lying to her for basically her entire life. Maggie asked Meredith to just be honest with her, but instead Meredith and Riggs just repeat the pattern of lying to Maggie and then wonder why Maggie gets so upset.
So its rather bizarre when the discourse on this moment keeps being switched around from Meredith lying to Maggie to Maggie being upset about Meredith's lying. Almost every comment or post talking about it downplays Meredith's actions and instead complain about Maggie 'acting like a toddler' or being 'butthurt'. And what no one mentions is that Maggie was angry for about a day, afterwards she was entirely supportive of Meredith and Nathan's relationship, so why do people act like she tried to sabotage their relationship?
The hate for Maggie in this situation feels so manufactured it makes me wonder if people actually watched this storyline, if their blinders for Meredith are that strong or are people just deliberately lying about Maggie to make her look worse.