Nah, I mean it's a polite fiction in those shippy fics.

In canon I take it at face value and Bilbo just never felt the need to get married, or met the right girl, or after becoming a Hobbit of Adventure never quite felt he fit into Hobbit life quite right again.

I also think that's why Frodo never married (his yearly illness from the Morgul blade wound aside), but that Sam retained enough "normal Hobbit" that he could go on and marry and have children.