Simon, CJ, Dean, & Henry: They kick everyone else out of the base so they have it to themselves and then they just order takeout, cuddle, & watch movies. They're not really fancy people and fancy restaurants stress them out too much, but Simon and Henry are very romantic people, so this is their compromise.
Sarah & Chloe: They buy an unnecessarily fancy hotel room for the night and have a blast doing random shit.
Marie-Kate, Jack, and Peter: The three of them would always go on movie dates together when they were all "single".
Lucas & his GF Mae: They also have a quiet night in watching movies & it's a very fun time.
Madeline & Peter: Valentine's Day is Madeline's birthday, so she forces Peter to go out for some fancy dinner with her. He hates every second.
Samantha & her GF Kelli: They go paint pottery or something else like painfully domestic for Samantha and they have a wonderful time.
Payton & Jason: Definitely fancy restaurant people, good times though.
Ava & James: They probably just hang out at home and cook dinner together and maybe watch a movie. No stress, but they wanted it to feel a little romantic.
Faith & Becky: At least one if not both of them forget that Valentine's Day was a thing, so the two of them just order takeout like any other night.