ANSWER:

Normalising free mixing like this is not permissible.

It is better to wait for a better option for a spouse or make it a condition before going through the proposal that he stops such haram activities. 

QUESTION: Here free mixing is normalised. Everyone I know (even students of ilm) follows opposite gender on snapchat & instagram. I don’t do it. I have a proposal. He does this, & my family sees no issue. He prays, has good akhlaq, & says he’ll maintain boundaries while interacting with other women. Should I accept the proposal?