Assuming too much.
We often make mistakes thinking we know how the people closest to us feel. We do more assuming than we take time to find out.
The most common mistake is the assumption that the other person's needs are the same as yours. So think you melding with yours and surviving means they can survive theirs.
In most marriages, sometimes we think that our spouse's needs are the same as ours, and in so doing, we completely skip over the crucial questions that takes a relationship to it's deepest level.
Many parents sometimes wrongly assumed their children are wired just the same way they were when it comes to expressing and receiving love and encouragement. They think it's of no need.
Best friends often stop asking questions of each other and instead anticipate what they believe the other would say.
It's very much easy to assume that the person closer to me is exactly like me, but it's never true. As a matter of fact. It's a dangerous assumption with devastating consequences.
In the case of most marriages. There are many husbands and wives who truly love each other, yet neither feel loved because each completely misses the target when it comes to meeting the other needs in terms of expression of love.
There are also many parents who really love their kids, but those kids doesn't feel loved simply because the parents aren't expressing it in a way those kids can see.
Many friendship today become distant when well-meaning people make false assumption and stop making the effort to learn more about each other. In every case the root problem is that in friendship, we all tends to give what we wish we could get. In doing so, we overlook that the other person's needs may be entirely different from ours.
If you want the people you love so deeply to feel loved when around you, it's essential to risk the awkwardness of asking them what their needs are. They won't tell you at first. Everyone wants to feel their problems in form of needs is safe with you.