When people say women are high maintenance. Is it refering to looks or personality or both? Please explain this to me.
It means the person (guys can be high maintenance too) requires a lot of your attention (and often money as well). You have to call them a lot, see them a lot, send love notes, flowers, etc. or they will feel neglected and look elsewhere. You must take them out frequently, spend more time with them than you otherwise would with someone else. In short, the person is demanding of your time and attention, this often translates into demanding of your money as well: dates cost money, trips/gifts cost money, running errands for her costs money, the finer things in life cost money. If you don't have the inclination to romance someone this way forget about dating the HM wo/man!
Even if you win his/her heart the HM factor does not go away; it may even become more acute. Beware!