recurring third with one couple, what are the unspoken rules

so this is a good problem to have but i need advice. couple in vancouver, we've played 4 times now over 6 months, all amazing, and it's clearly becoming a "thing". but nobody's talked explicitly about what it IS. like... am i allowed to suggest a date or do i wait for them, can i text her between plays just to say hi or is that overstepping, am i exclusive with them or are they playing with other singles too, do i bring it up or do i just let it ride. dont want to overplay my hand and lose a good thing but also feeling a bit in the dark about my actual position here