Looking for romance manga with cold/shy/awkward/tsundere male lead but goes overprotective when the female lead is threatened or endangered. Usually with angst because of feelings of inadequacy or guilt of failing to protect >///<

If possible the female lead is an emotionally strong or strong person, and even though she's weak she's hardworking or smart (no Shinjo Mayu style of idiots).

No yuri/yaoi/shounen ai/shoujo ai. Smut is welcomed.

Example of what I'm looking for
Kanata Kara
Mahoutsukai no Konyakusha

How about this,

I'm a Villainous Daughter, so I'm Going to Keep the Last Boss

Although you can argue about whether or not it’s a romance, the characters in Fairy Tail typically go absolutely crazy when one of their own gets hurt. It’s immensely satisfying when they do since they often get held back or calmed down by their loved ones.

It’s a longer series, but has a sense of fun and adventure with different relationships throughout.

**My Personal Favorites: ** Skip Beat, Tokyo Crazy Paradise, Ashita No Ousama, Gokusen, Until Death Do Us Part, Perfect Girl Evolution, Ouran Highschool Host Club, Kisu yori mo Hayaku.

falls back with nosebleed, killed by the sexy

Akatsuki no Yona comes to mind. Romance is more of a slow burn, and ML is not exactly tsundere but he doesn't act on his feelings until later (for certain reasons). FL is definitely mentally strong and works hard.

Seems like the trope is popular in isekai light novels and webnovels, really resembles mahoutsukai no konyakusha, both in plot and art style. Thank you for the suggestion!!

A recent series that I'm reading definitely has that kind of male lead It's Mine. Yes it's a stalker male lead, so it's a bit more than "shy/awkward" kind of guy (still fits the bill), but unlike female leads from this kind of genre, she is very strong willed. Also these might fit (from memory):
Beast Master
Abide in the Wind
Shinobi Shijuusou
Bastard (HWANG Youngchan) dark like It's Mine (even darker, but the ML is very protective of the female lead, highly recommend it even if it doesn't fit the bill)

I'm in idol hell T.T

Mahou Tsukai no Yome absolutely fits this trope.