Lotusblossom, you have a very interesting perspective. I understand your point about not bothering with total honesty when it comes to familial love, but I don't see romantic love quite the same way. I think the biggest distinction for me is that there are lots of things that bind a family together, other than love, e.g., common history, other family members, money, property, living arrangements, etc. If you don't particularly love a family member, they're still pretty much going to be a member of your family....the stakes in telling that kind of lie are pretty low. However, the only thing that typically binds a gf/bf together is liking/loving each other. So if the liking/loving is not real, the the whole foundation of the relationship is called into question.
I also agree that actions are more important than words - it's more important to act in a loving way than to say "I love you," (at least that's my interpretation of your post). However, I think the OP's circumstances are different. She doesn't love this guy. She may not even like him well enough to remain in the relationship. She may just be straight up incapable of love. In her situation, telling this guy she loves him is building the relationship on pillars of salt and sand, when he thinks it's being built on bedrock. It's not that she feels it and can't verbalize it - she simply doesn't feel it. In her circumstances (IMO), it would be much kinder to tell her bf the truth, and let him make up his own mind about how to move forward.
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What you feel is what you are and what you are is beautiful...