A lot of shoujo manga titles are just mawkish to the point that I quit reading manga at all and switched to webcomics. I love romance stories, but what shoujo does (and shoujo inspired comics) is more than enough. Especially overexagerating already exagerated proportions, too much special effects, too much forced sweet comedy, dramatic-and-so-romantic poses with normal dayly events (for example bumping into someone, accidentaly touching each other etc.)...
As @vothnthorvaldson said, mawkishness has its own purpose and time to be good, but really, romance titles (in general), really often cannot come up with good balance.
For me, mawkish aspect is worse when it comes with storytelling. Most of the cliches in romance are used so wrong. For example: there is this love triangle for the sake of being love triangle, childhood friend who is secretly in love with main character, the main character unnecessarily becoming too bashful around his/her love interest, the pacing of the story being too fast, the main heroine who used to be kind of badass and then losing her personality when loving someone ("Watashi ni xx shinasai" being one of the titles that infuriated me the most with some of those cliches).
But what's the most important - there have to be balance! Even cliche may be good.
This is why I love those funny talks in Nier:Automata between 2B and 9S (there's a lot of drama, so the conversationd makes you think: "Aww, they're so cute together!", eg, when 2B called his partner "Nines" in the castle).
This is why I don't like Cloud x Tifa shipping (because I read too many stories with childhood friend cliche for my own sake)
(sorry about video game references, that was first that came to mind)