Being in a relationship is not consent.
"We've had sex before" is not consent.
Consent to one act is not consent to all acts.
If they aren't sober, they can't consent.
The absence of "no"is not consent.
Flirting is not consent.
Silence is not consent.
If you have to convince them it's not consent.
If they don't feel free to say "no" it's not consent.
ONLY AN INFORMED, SOBER, FREELY-GIVEN, ONGOING, ENTHUSIASTIC "YES!"
IS CONSENT