I mean, honestly not to be negative but most people’s first relationships do not end up fruitful for long term. Also, if you had feelings for someone for two years, which died out within only five months, it might’ve been the romanticism of longing/pining that attracted you to begin with, and when those expectations weren’t met, you naturally felt that it was the equivalent of falling “out” of love. I wouldn’t feel bad about it, because in the long run it’s more hurtful and unfair to her for you to pretend to like her which she would eventually realize, and then the split would be messy and most likely more difficult than needed. I would explain to her that you’d like to preserve your friendship if she was comfortable with that (she probs won’t be but sometimes people just need time so don’t take it to heart, just respect it) and if that’s also what you want. Just remember that it’s not your responsibility to maintain her happiness after you’ve broken up, you just have to respect your feelings and hers but don’t give up or sacrifice your happiness to keep her happy. Honestly tho, the way you care about her so much to worry about how she’ll take the breakup sounds a lot like love to me, so it might be worth it to talk to her about it first and figure out why you feel like you’ve lost that spark to begin with. Some people just need to reignite a passion or look at the relationship from a new perspective to realize that their loss of love is more internal than an actual issue with their partner