relationship problems! HELP!

Okay so for the first 3 or 4 months of our relationship, everything was great. Me and my boyfriend fit each other like a key. He was protective, sweet and caring, and very fucking handsome - and he still is! But we've been having some problems lately. And idk if it's the cause of why I'm feeling this way, but idk. So for the past month or so I haven't been showing my boyfriend affection. And he noticed it today. Him talking to me about it made me realize it's true. And I told him that I lost interest of showing him affection, but I still love him and I always will. He started crying and asking me what happened and I honestly couldn't answer that. It could be because of the problems we've been having, but I'm not sure. I just lost that "spark" every time we'd kiss or touch. I feel like a fucking piece of shit! Idk what to do! I do love him, but idk if I love him as a boyfriend... What should I do..?