I'm not sure if Goldenflower really did love Tigerstar. He didn't care about her, and only took her and Sasha as mates so that his blood would run in the clans.
Before he died, he loved Goldenflower, and then Sasha, in the Warriors manga.
Everyone knows that Sasha fell in love with Tigerstar accidentally, because she thaught that Tigerstar was a kind cat. But Tigerstar loved Goldenflower and after regretted mating with her, because he got such kind hearted kits. He also regretted in mating with Goldenflower because he could have been deputy after Lionheart , (if Tigerstar killed him Goldenflower will never forgive him, because Goldenflower snd Lionheart are littermates) He mated with Sasha because he wanted strong determind kits, like Sasha who was brave enough to leave her Kittypet home. Goldenflower never knew Tigerstar was evil but she did, took care of her kits no matter what happened. Sasha left her kits. Goldenflower knew Sasha. She was not jealous, she knew what they would become. She knew the Clans would be in danger.
Yes, Goldenflower is Tawnypelt's mother and Tigerstar is her father.
Although Tigerstar did mate with Goldenflower, he did not really love her. It is more likely that he only mated with her so that he could have children, and he wanted to raise them to be like him.
When Goldenflower was mates with Tigerstar she didn't know that he was evil yet. I don't really know the answer for your question, but I think no. Sometimes even if their mate is evil, they still love them and sometimes they don't.
Goldenflower and Tigerstar. His sister's name is Tawnypelt.
I don't think Erin Hunter really tells us in the books. Plus, Tigerstar is so sneaky that we may never know. I think it might have been when he was with ShadowClan and trying to take over the forest, though.
Most likely not, if she is then it is not recorded in the warriors series.
Tigerstar admired Leopardstar's strength and leadership abilities, but there is no evidence to suggest that he was in love with her in a romantic sense. Their relationship was more focused on political alliances and shared goals rather than romantic feelings.
Goldenflower. He is the half-brother to Brambleclaw and Tawnypelt. Goldenflower had a unknown tom as her mate and gave birth to Swiftpaw. Then, Goldenflower had another mate, Tigerstar. She gave birth to Brambleclaw and Tawnypelt. Brambleclaw, Tawnypelt, and Swiftpaw shared same mother, but had different fathers.
Bramblepaw is Tigerstar's and Goldenflower's kit.
Goldenflower may had had other kits before into the wild, but her known kits are Swiftpaw, Brambleclaw, and Tawnypelt. Swiftpaw's father is unknown, but Brambleclaw and Tawnypelt's father is Tigerstar