I have noticed that some people will profess their love quite easily and these people are considered very loving people - emotionally open.
Other people will reserve their professions of love to just a few or even none - and these people are considered emotionally removed.
It is possible that the latter group, though, is even more emotional than the first group in that they have put such a value on the emotional commodity that they cannot simply say it unless it is being felt at a profound level and they feel safe in making such a confession.
When someone from Group A and Group B are together, things can become confusing as If the First group person says they love the second group person, the second group person might interpret the first group to be saying it on the level that they perceive it - especially if they want to hear it this way. Likewise, the A group could misinterpret the B groups withholding as an emotional removedness and feel unloved.
There probably is no solution to this but awareness and patience.