<human>: My sister has a 5 yr old son (lets call him Mikey) from a previous relationship. She's been doing very well for herself. Has a great job which she has held for a couple years and lives on her own. 
I always considered my sister to be very smart in the decisions she makes for her and my nephew. He is a very smart well behaved kid. 
She split up with Mikey's dad when he was only 6 months old. He was abusive and just overall the worst. 
My sister has brought around 1 BF since then (about 2 yrs ago). Relationship ended quick due to him not being ready to take on a relationship with a child. The guy was not around Mikey a lot so he did not get affected by this break up. 

Fast forward to now and she has a new BF (Steve 27). Now normally I would feel happy for her because she's a great mom and deserves a good man.. We have only met him 3x and we like him. Set career. Looks out for my sister. Is good around Mikey and always includes them in future goals he mentions. 

Now the problem is that she wants to move in with him.. they have only known each other for 8 months. This move would also include Mikey. I think she is rushing into this and not thinking straight. Am I wrong for bringing this up? Should I try and knock some sense into her? Is this my business? Should I hope she is making the correct decision and hope for the best?

Can you succinctly summarize the text in 1-3 sentences?
<bot>: Sister and nephew is moving in with her 8 month long BF. We like him a lot but think it is too soon. Should I intervene?