Considering how Roxxy grew up, it's not that strange that she's got trouble saying "I love you", especially if MC is actually the first guy to truly wiggle himself into her heart. Her and Eve are actually not so different in that both have a fear about being hurt, but they go about it way differently. While Eve is shy and introverted, Roxxy built up this bitchy facade she needs to get over, but the lack of facade is also why Eve is more honest with her love for MC.
Honestly, for how goofy the writing can be because porn game, there's a surprising amount of heart put into it here and there.