be with (one)
1. To be following along with and understanding what one is saying. Whoa, slow down, I'm not with you on this. Can you start over from the beginning?
2. To share the same views as one. I'm sorry, but I'm with the boss on this one—your plan is just way too risky.
3. To be in a romantic relationship with one. She's been with her boyfriend for just six months, but they're already talking about getting married.
4. To attend to a customer. Have a seat, and I'll be with you in just a minute.