Loving someone and being lovingly with someone are two different things, different feelings. Don’t infer the same from these two. You can love very few, parents, boy friend/girl friend, best friend etc. But at the same time you can be lovingly with many including those whom you admire, whom you take as an inspiration, with whom your time passes nicely/friendly etc.
One point here, ironically, when the people you love commit some mistake you may at times take it seriously and wrap them up; and when the people with whom you be lovingly commit the similar mistake you give helping hand in rising them up from the deep displeasure. On the contrary, in case of some other mistakes, you can easily forgive the ones whom you love, but can not simply go ahead easily with those whom you otherwise are lovingly.
Mistake or misunderstanding, whatever, it makes us think differently for person to person, incident to incident. Nothing wrong with such! Never mind if you can settle it up with your best friend for a mistake/misunderstanding and can not do the same easily with your boy friend/girl friend for similar mistake/misunderstanding. These two persons are two different entities with two different expectations from you. All that matters most of the times is the commodity called expectations. They can not be sacrificed, in fact they be there no matter what. They just frame up themselves deep within.
I suggest, you try to unravel such cases by digging deeply inside your own expectations and how they have been framed up. Most importantly, understand if you have ever communicated your expectations to your friend/partner. If you haven’t, share the mistake. If you have, try to solve it out and talk it out with a positive outlook and a hope to resolve. Never go after the culprit rudely as in case of most of the disputes there’s the involvement of two people.
Don’t confuse yourselves by asking the questions such as, “Why I can not take it easy with my partner as I can do it with my friend?” or “vice versa”. At times it ultimately leads to the grand question, “Do I love him/her really? Is this all love?”
No, never enter that mode. If it has happened with you, or happening with you or would happen with you, please be informed that its one of the quite common happenings across the earth. Don’t ruin your relationships with confusion of thoughts.
Relationships shall be made or broken with clear understanding but not without it.
PS: I’ve seen many couples/friends who are worried with such incidents/feelings between them. I hope you may find this helpful when you have to face it.