when you lose feelings, it means when you no longer have interest in your significant other. you could be occupied for 3 days, and then your boyfriend tells you he's lost feelings. he could tell you he's "so in love with you" only for him not to be anymore just because you haven't spoken for a little, and you've been a little weird. but that's normal, I guess for him it wasn't!
some random dude: I lost the game!
you: yeah the same way my boyfriend lost feelings.