Moumate Wa Dekinai. - 405-Goushitsu No Banken-Kun summary:

“I might be a bit heavy, but please take care of me.”After breaking off a relationship heatedly, she's proposed to!? The blunt and mysterious coworker Kido-kun is only protective towards Momoko. Because of this, he's given a nickname, “Guard Dog”. Momoko is happy since she's secretly in love with him, but is unsure whether it's unrequited. She can't figure out his intentions and struggles every day. One day, Momoko is being stalked by her ex-boyfriend when she's saved by Kido-kun. “I'm the one that's dating Fujita now. Stay away from Momoko from now on!”. Even if it's a lie, her heart flutters upon hearing that, but Kido-kun gently pushes her down saying “That was half a lie and half my selfish desire”...!? It's her first time being held so gently, and she's caught in the pleasure.