What a difficult choice !!! Please help Auntie Aggie (an Agony Aunt columnist) to answer to this poor chap !!!

Dear Aunt Aggie,

I have a problem that I hope you can solve. Three years ago, I met a girl,A, for whom I completely fell head over heels. We started going
together and soon became an item.

Recently there has been talk of marriage. During the same time, a good friend of mine, B, broke off with her boyfriend and sought consolation in me. Being a good friend, I was always there for her and before I knew it, started having feelings for her too.

This was of course not known to A,with whom I'm still going out. At the
same time, for reasons I am not sure of,I have decided not to tell B about A.
Not too long ago I met B's family and B's sister, C, took a liking in me
and asked me to join her and her friends for an outing. Not wanting to
disappoint her, I obliged, not letting B know. At the outing, I met an old friend, D, whom I haven't seen for a long time. She had been away in
Australia for the last 5 years. She had returned because her uncle has just died.

Even though she wasn't close to her uncle, he had left her, as inheritance, a house in Sydney and also all his money in his Swiss bank account. I understand that this amount is more than enough for her to live very comfortably for the rest of her life. Whilst we were talking, D confided in me that she has always been attracted to me. She told me that she is still unattached and intended to remain so until she hears news that I'm already married. She also told me that she had planned to contact me, disclose her true feelings to me if I'm still single and had hoped that by some chance I may even consider coming to Sydney with her. She felt that the fact of us> meeting so coincidentally was due to some kind of fate. So I think I would like to meet her in sydney.

Now, you can see the fix I'm in. So, my question is.........'Should I fly Singapore Airlines or Qantas???"