Brothers wife behaviour?

My brother is married since 8 years. 2 kids. his wife accepts gifts from me. doesnt tell her man. she made allegations i was gifting behind her hubbies back. now she is staying seperately with her hubby and kids. once when my brother was at my home i called her over phone. asked if i come to her home. she said come but dont tell her husband about it. i went and met her. she was all alone at home. once recently i proposed to her. she just laughed at. i gave her couple of gifts for her. after she complained about me. She accepted it. Now what i want to know is is she taking me for a ride as i give gifts. or is she interested in me. If she wasnt positive she would not talk to me after i proposed to her. Please advice.