serious about someone
serious about (someone)
Wanting or committed to a permanent or long-term romantic relationship with one. I know he's getting really serious about her. I wouldn't be surprised if he proposed in the next year or two. I don't really want to get serious about anyone during my time in college. I'd rather be free to do as I please.
See also: serious
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
serious about someone
mod. in love, or almost in love, with someone. I’m afraid I’m getting serious about Bill.
McGraw-Hill's Dictionary of American Slang and Colloquial Expressions Copyright © 2006 by The McGraw-Hill Companies, Inc. All rights reserved.