Exactly right! Love interests will never be required for game progression, but certain story events may have variations based on who Silk has developed a bond with. The vast majority of stories and scenes for love interests will be found in each LI's personal quest, though.
Silk will meet all love interests via exploring the patrol map, but it's player choice on if she wants to pursue them romantically. I'm trying to develop love interests with certain niches in mind to make them stand out so some characters may provide certain kinks, but those kinks are not planned to be exclusive to any given character.
For example, if Robbie Reyes (Ghost-Rider) wins the ongoing poll, his scenes will feature a good deal of bondage by his chains. Spider-Woman is also planned to have bondage related scenes, though. As such, both routes would eventually accumulate the bondage kink.
Finally, there are some loose ideas to have certain LIs crossover with others but they are the hardest scenes to write, most expensive to commission, and it certainly is not planned for every potential matchup. I'd only really try to do this for combinations that really make sense.