A committed open relationship based on boosting the love and affection opportunities available for one's partner
absence makes the heart grow fonder
One feels more love or affection for those one loves when parted from …
open doors
To lead to opportunities or social advantages.
keep one's options open
To not commit to a decision, to keep various options available.
on the table
Open or available for further attention or action.
chat up
To talk to (someone) in a friendly, open, or casual manner, sometimes …
do the math
To determine the explanation for or precise nature of a situation, suc…