I think they nice and I know Mabel is crazy also being mean to her brother Dipper then started  weirdmageddon thank to her just because I making ship of two of them that doesn't mean I like her also she make Dipper feel horrible and ridicule also Mabel never learn her mistake anyway  on season 1 ep15 she first met Mermando then got along at night at the Gravity falls swimming pool he miss his family she help him to get back to his family Dipper the night guard try to stop her stealing the pool  equipment and now he know why the weird part he did the CPR she took the picture that just sad anyway they put Mermando in the sea Mabel give Mermando the megaphone or something she give it to him then he kiss her like this

When he left to see his family on season 2 she got another letter from him when she read the letter Mabel was heartbroken because he got marred to stop the War it sad they not together

so do I ship them together fine