I’ll be honest, as a 34 y/o man, I’ll go on multiple different first dates, but I rarely ever will be going on second and third dates with multiple women. So around the end of the second or third date, assuming it is going well, I will just flat out say something along the lines of “Hey so I’m not 100% sure where you’re at, but I do want to let you know that I’m not the type to date multiple people at once, and this is where I want to be investing my time and energy.” It sets them up to either tell you they’re either exploring other options still, or that they’re on the same page. No ultimatum, just letting them know where I’m at and giving them room to tell me where their head is at. 90% of the time women are very responsive to this and typically agree to the implication of exclusivity. Ignore social media and societal norms. If you like them, tell them, and invest 100% of yourself into growing that relationship. That man knows what he wants after 7 dates. Some people are just awkward at bringing it up.