I have played through Starcraft, Starcraft Broodwar and Starcraft 2 Wings of Liberty. Yet I do not know if Jim Raynor and Sarah Kerrigan had some kind of real love relationship.
Sure there was some flirting, but was there more?
I am asking this because I find it quite confusing that in Starcraft you had like 2-3 missions with Kerrigan as Terran and in Starcraft II Jim seems very attached to her.
Best Answer
It's been ages since I played the game, but...
... When Jim and Sarah first meet, there's a definite bad first impression (she's a telepath; his first unguarded thought when he meets her is about how well she fills out that tight uniform; she calls him on thinking it), but a few missions later, they're on first name basis -- enough that when Mengsk orders Kerrigan to protect a nascent Zerg hive from the Protoss, Raynor protests loudly about the danger, and only acquiesces when Kerrigan tells him to have faith because she trusts Mengsk has a good reason for it.
Mengsk's subsequent betrayal of Kerrigan to the Zerg by ordering all air forces to withdraw when the Zerg start overrunning the base is what enrages Raynor to the point where he decides to quit, and his escape from Mengsk's new empire ends the Terran campaign.
The first - and pretty much only - mention of their relationship during the Zerg campaign is during the mission where the Queen of Blades hatches from her Chrysalis -- apparently, some kind of telepathic emissions were manifesting in Raynor's dreams and called him into the area containing the Chrysalis, where he has a few heartbroken words when he finds out what Sarah turned into and that the Queen of Blades is absolutely not interested in being rescued.
For more references, see here and here on the official Starcraft wiki.