as a stand alone with that question I will say it means just friendship.
But nowadays there are all types of relationships, things are often not all black and white... there are people who are friends with benefits, in open relationships, or just "dating" casually and with no commitment, then there's serious dating, boyfriend/gf, exclusive...
From experience I will tell you that I once read on my ex and the woman he left me for, they used to get the "lovers" card a lot, they were romantic and dating for a few months, then they started getting the death card followed by happy cards, in particular these cards
9 of cups, 3 of cups, sun, etc..... their readings were very happy! and I was devastated, lol...
... I later found out, they actually broke up their "dating" or romantic relationship (meaning dating with a romantic purpose) but both had agreed to just be "friends" and they had talked about were they were headed relationship wise and he was not interested in pursuing a committed relationship, and she was OK with this.....
Their cards used to be Sun, 3 of cups, 9 of cups, World, etc.... they had a lot of interests in common and were still seeing each other, going to events, etc... so I do see the Sun card as a really positive one were two people are connected in a special way, but not just romantically. They never ended up getting involved as a couple.
also, I would assume that people who are in love must also have the Sun because it's such a positive card, the meaning
depends on the question asked.
anyhow, so yes.... the lovers, cups, etc was romance and dating, then cards changed to Sun, 3 of cups, 9 of cups because they had talked about their relationship and agreed to just be "friends".....
so look for surrounding cards... but during breakups were both people agree to end in good terms (specially if they continue hanging out) my cards tend to change from lovers, to the breakup (8 of cups, tower, death, etc...) and then continue with happy cards like Sun, 3 of cups, 9 of cups.