communicate secretly with / be in secret touch with

have illicit intercourse with / have relations with / have an affair with

be in good use / be in common use

<<communicate>> get through to *someone / communicate / make *oneself understood

make *something extend to / ensure that *something reaches [its destination] / get *something connected with / make *something reach [a destination]

open *one's heart to

report / announce / inform / say / tell

*one's second self / *one's biggest support / most reliable *person / prop and stay

*one's resource / *one's last resort / prop and stay

errand [boy] / messenger