Does it sound fluent when a sportsman says “I’m in love with sport” or a musician says “I’m in love with music”? Or there are better ways to say this?
The OED does not specify that being in love (with) is only applicable to a person or other living thing.
a. in love (with): enamoured (of), filled with love (for); (in extended use) very fond (of), much addicted (to). In quot. a1398: †in heat (obs.). See also mad in love at mad adv. 2b and madly in love at madly adv. 2a.
In fact, it provides some quotations that describe being in love with things:
a1616 Shakespeare Two Gentlemen of Verona (1623) ii. i. 76 I was in loue with my bed.
1969 J. McPhee Levels of Game 10 He is in love with his work. He knows the exact height and tensile strength of the corporate ladder.
However, the usual way would just be to say I love [sth.] See @Lawrence’s comment.