Well, Sonic is a hero at heart. So when Amy gets hurt, he would first assess the situation calmly, but inside he'd be worried. He'd make sure she was stable and then look for the cause of her injury. If it was an enemy, he'd go after them. But he'd also be very gentle with Amy, talking to her softly and reassuring her that she'll be okay. He'd do whatever it takes to see her back on her feet again, like finding special herbs or items that could speed up her healing process.
Sonic would probably be very shocked at first. He trusts Amy, so her betrayal would be unexpected. He might initially try to talk to her to understand why she did it.
Amy might initially be in denial. She could think that Sonic didn't really mean to break her heart and that it was all a misunderstanding. So she might try to act normal around him at first.
Often, she will be very protective. Amy would try to shield Sonic from any further harm. She could stand guard over him and not let anyone or anything get close that might pose a threat.
She can also get angry. After being hurt, Amy might lash out at Sonic, telling him how his thoughtless actions have affected her. In some fanfictions, she'll try to make Sonic feel guilty by reminding him of all the times she's been there for him. And sometimes, she'll try to change herself in an attempt to get Sonic to notice her in a different way, like trying to be less affectionate or more like Sonic in her adventurous spirit.
Some fans might be very shocked and disappointed. Sonic and Amy have a long - established relationship in the Sonic franchise, and this would be a huge deviation from what they expect.
Tails would probably be very helpful. He'd use his intelligence to make sure Amy has a comfortable pregnancy, like creating special devices for her. Knuckles might be a bit awkward at first but would ultimately be very protective. He'd stand guard to make sure no harm comes to Amy and the unborn baby.
Their friends' reactions would vary. Tails would be enthusiastic and start thinking of all the ways he could help. He could create little gadgets for the baby, like a mini - sonic - speed - training - device when it gets older. Knuckles would be more of a protector. He'd see it as his duty to make sure the baby is safe, especially since Sonic is his friend. Rouge would be the fun auntie type. She'd bring stylish baby clothes and tell the baby all kinds of exciting stories from her travels. And the Chaotix might be a bit clumsy but well - intentioned in their attempts to interact with the baby.
Their friends would be really excited. Tails would probably be the first one to offer his help. He could use his mechanical skills to build baby - friendly gadgets. Knuckles would be a bit more gruff but still happy. He might offer to train the baby in self - defense when it grows up. Cream and Cheese would bring little presents for the baby, like cute toys or delicious Chao fruits.
Sonic might be really confused if he is under the effect of the love potion. He's always been independent and suddenly having strong romantic feelings for Amy would be a big change. He might try to fight the feeling at first because it's so alien to him.