Not just childhood friends. /Bethrothed/ as children to each other. When he decided to escape, he full-on left town. And it's probably because her father is the head of a crime syndicate.
You come back, she shows up, her dad lets you off the hook for fleeing /only because she still wants you anyway/, but makes it plain that if you hurt her, he'll take action. And that if she's under your roof, it's your responsibility to protect her.
On top of all of this, she /works with her family/ in the crime syndicate, specializing in espionage. She may not be the best fighter out there, but she's unfathomably dangerous.
So, she's gorgeous, rich, a master of extracting information by subtle means OR torture, extremely well-connected, you've known each other so long and so well that you can basically predict almost everything the other will say or do in general, and if she chose to, she could cause the entire force of a cartel to come crashing down on you specifically with murderous intent.
At no point have I considered the MC to be wimping out in dealing with her. Hell, he talks back to her regularly. Considering the danger he could be in if she actually got legitimately upset with him, it takes big brass balls to tell her no or contradict her about much of anything at all. And to top it off, she has her own personal samurai that would kill you in a heartbeat if given the word, and is staying with you too.
Yeah, MC is not wimping out. MC is being /smart/. Plus, given that she doesn't really give a shit if he's screwing every girl that works for him, and still wants him? Yeah, this means that if he caved and accepted the betrothal their parents set up so long ago, he gets a super-hot wife that can easily help him crush all competition, and becomes a potential successor to a crime syndicate with status equal to the nobility. That's really not a bad deal at all.