Recommendations

Both are dramas with a modern day FL who finds herself in history.
................................................................................

Both are mini dramas with a modern day FL who finds herself in history.
................................................................................

Both are mini dramas with a modern day FL who finds herself in history.
................................................................................

Both are mini dramas with a modern day FL who finds herself in history.
................................................................................

Both are mini dramas with a modern day FL who finds herself in history.
................................................................................

Both are mini dramas with a modern day FL who finds herself in history.
................................................................................

Both are mini dramas with a modern day FL who finds herself in history.
................................................................................

So In first love again....his first love is reincarnated each time because of the love that connected them. So he gets reborn and reborn each time until they can be together.

In Once Again, the ML kinda like time travel? To go back to that moment he caused trauma in his first live's life.

What's similar is that if you look closely you'll notice that this isn't the first time...the ML had already travelled in time before and it's like a constant loop because eventually the Mal's "lover" would make the same choice again.

Anyway, if you like the one, you'll like the other.

in both dramas, the ML and FL share their power with each other to help the illnesses they are suffering from.

So here are a few similarities:
- the ML /FL underwent a gender changing surgery (in DSILY female to male and in TFL male to female)
- the couple knew each other since childhood (in TFL the ML is the not-blood.related uncle of the FL)
- both main leads return (among other things) because of their love

Actually over all the gender change is the only similar trope, as you might have notice TFL is not a BL. But TFL is so good as well. It definitely does not have the same vibes as DSILY, it‘s a bit darker and (of course) dramatic and emotional (not in a feel-good way). But anyways you should check it out!

Also a Thai GL Drama Series. Based on the trailer even the ship dynamic is a bit similar - ex. one more known and rich character in the ship with not so good social skills.

Hello there is set in an earlier time period but there is spiritual powers in both. at first, the male lead in both dramas is cold and distant but as he gets to know the female leads he warms up. some of their conversations are really funny. both dramas start at one small sect then move to others sect for information and or medicine needed

the main lead acts stupid but is actually quite smart. the male leads in both shows have 2 different sides to them. He falls in love with someone he didn`t expect to and doesn`t want to admit it until she is put in danger.

Both are warm and cozy romantic melodramas. Both have seasons in the title and they actually occur during those seasons. I also suggest watching them in the season they are set in. The female lead in OSN and male lead in SS are librarians. Both male leads are low key and total green flags.

In both drama one partner is an alien and another one is a normal human being.In my girlfriend is an alien it's the girl who is an alien and in starcrossed lovers it's the boy.

Pardon my grammertical mistakes