In Season 6 she didn't love him, but she WAS starting to. That's kinda why she reacted so badly to his every sweeter action.

I think she started loving him in S5 but didn't grow to truly him until S7.

I think in season 7 when she started loving him

I think the was a spark in S5, but the real feelings she started feeling for him in S6. However, the true love came in S7 when Buffy finally let herself love him, after seeing how much he loves her and how he is ready to go through everything to be with her. Buffy realized that Spike is the one to be on her side no matter what. She wouldn't let herself love him, because she was afraid of her own feelings for him, also she wasn't still 100 procents sure in him, but in Touched I think she finally realized that he is the one and that he deserves her and that their love is real.

In S6 cuz he was the only one she felt a true connection with, tho it wasnt healthy per se. Her feelings became stronger & easier to deal with/have in S7.

Ive only just finished season for the first time and I'm starting to like them alot

I think that she started to fall in love with him towards the end, but didn't want to fully admit it until Season 7.

I think she started to in season 6 and only realised/admitted it in season 7.