Putting in roughly half the down payment and making half the mortgage payments. How is that even a question?
I know, it seams obvious to me. But there were ridiculous comments like:
"It's your boyfriend's house, you are lucky to get 10%."
(From what I understand they haven't bought the house yet but the only reason it will be "his" is because he doesn't want to put her on title.)
"She has another property so this should be his"
(That house was acquired before they were together so it shouldn't factor into the equation.)
"It is like paying rent, you don't expect to own a share of your landlord's place."
(First she is putting 10% cash in, second couples and landlords are not the same arrangement, third maybe if a rental agreement at an agreed upon price was written up it would be clearer but as is asking her to pay 1/2 the mortgage it is crazy.)
There are some logical solutions like "she should only pay 10% of the mortgage not 50%"
There is also some tax talk I don't fully understand. Perhaps in the UK you can't own 2 properties without taking a tax hit. She may be trying to keep her rental as her primary residence and he would have this new place as his primary residence to avoid future capital gains tax. I'm not in favor of sneaky maneuvers like that it that is what they are trying.