I'd suggest searching on Tumblr as well. There are often posts that link to or recommend 'Mass Effect' fanfics. Some of these will be centered around Shepard's interactions with the crew in a platonic or adventure - related context. You can also join some 'Mass Effect' fan groups on social media platforms like Facebook or Reddit. Members there are usually happy to share their favorite non - lemon fanfics about Shepard and the crew.
There are also some official 'Mass Effect' extended universe novels that touch on the relationships between Shepard and the crew in a non - sexual way. These can be a great alternative if you're looking for more in - depth stories. For instance, they might explore the backstories of the crew members and how Shepard comes to rely on them, which is really interesting.