Does someone who can't say "I love you" actually feel it?

Possibly. Some people feel love deeply but struggle to verbalize it due to attachment anxiety, childhood modeling (parents never said it), or cultural background (some cultures show love through action, not words). The question isn't whether they feel it; it's whether they're willing to express it for your sake.

Should I accept a partner who shows but doesn't say?

If their words-of-affirmation is secondary and their acts-of-service is strong, you might adapt. But if hearing "I love you" is your primary love language, this is a fundamental mismatch. Some people can't meet that need no matter how much they care. That's incompatibility worth addressing.

How do I ask for words without seeming needy?

Be direct: "I need to hear that you love me. I feel most secure when you say it, even if you show it through actions." Most partners respond to this honesty. If they refuse, that signals they won't adapt to meet your needs—which is the real compatibility issue.