Both Renly & Loras are gay in books, George has confirmed
link, but it is never been directly said in the books. But it is hinted several times.
Few examples:
Now sheathe your bloody sword, or I’ll take it from you and shove it up some place even Renly never found. Jaime to Loras
When the sun has set, no candle can replace it. Loras about Renly
Renly’s little rose? I doubt that. Oberyn about Loras
We had...we had prayed together that night. Loras about Renly
...I got Margaery. You’ll be pleased to know she came to me a maid.
In your bed she’s like to die that way. Renly & Stannis
And it relieved him of the difficult task of trying to find lands and a bride for a third son, never easy, and doubly difficult in Ser Loras’s case. Petyr
Loras is valiant and handsome and we all love him dearly...but your Imp will make a better husband. Garlan
Renly also has a reputation for being well into fashion and the best dressed man at court
And instead of a standard Kingsguard, Renly decides to call his group the “
Rainbow Guard.”