He said he’d protect her and he probably feels that he’s the only one who can do that.
Being the rumbelle fangirl I am, I also chose Gold. I can see him easily becoming over protective and not letting her out of his sight. This is not completely a bad thing. Yes Belle has always strived for freedom (which she deserves) but after all the pain she has been put through, she could use a shoulder to lean on.
I also voted for Gold. I can see him inadvertently alienating Belle from the rest of the town because of his over protectiveness towards her.