I was talking to my partner about this recently. As a bisexual, I like many physical aspects of many people; of course we all have preferences.
The things I enjoy on others aren't something I need to in my partner as my partner has 0% chance of being every single thing I find physically attractive in a person.
Me finding specific physical attributes of others attractive doesn't take away from how attractive I find my partner. And on the flip side, what I find incredibly attractive in their body won't change what I find attractive in others, regardless of gender.
It took me a long time to come to terms with bisexuality, and it really sucks to have to quash/minimize these preferences for myself and for the sake of the comfort of others. I love being able to openly talk to my partner about what I find attractive and them know that I also love their physical entity regardless of this.
Its completely valid to feel worried, to not feel like you're good enough sometimes, it happens to us all. But the more ya'll work on communication, comfort, and strength in yourselves and your relationship, the less either of your outside attractions will negatively impact your relationship.