-다 보면

If you keep -ing, If one continues to..., Doing... over time

Explanation

This expression indicates that if the action or behavior in the previous clause continues, then over time the result in the following clause will occur. It is also written in the form -다가 보면.

Details

Neither the past nor future tense can come before -다 보면, and the past tense is not allowed in the following clause either.

그 친구를 계속 만났다 보면 좋아질 거예요.
그 친구를 계속 만나겠다 보면 좋아질 거예요.
그 친구를 계속 만나다 보면 좋아졌어요.