Armin and Sandra have been married for 5 years. They live together in a house in London which they purchased together 3 years ago. The house cost 350,000, of which Armin provided 50,000, Sandra provided 20,000 and the remaining 280,000 was gained by a mortgage in Armin's name alone because Sandra was not working at the time. The house was also registered in Armin's sole name. Armin said to Sandra when they purchased the house:

"Don't bother yourself about the legal stuff - we can put you on the title when you start to earn some money."

Sandra started working shortly after this in a good job and paid some of the mortgage payments. She also paid for the majority of the household expenses. Armin was from a wealthy family and did not need to work - he spent most of his time rebuilding classic cars in the garage which he sold for a modest profit.

Armin and Sandra have good friends who live nearby, Eren and Gabi, who have been in a relationship for 12 years and have four children aged between 2 and 10. They are married. Shortly after they met, Eren and Gabi got married and moved into a flat which was mortgaged in Eren's name alone, and his was the only name on the legal title.

Armin has invested money into Eren's crypto-trading business. Eren has suffered a major loss in his business and he is afraid that Armin will ask for his money back and make Eren bankrupt once he gets to know about the loss. To avoid being homeless, Eren transfers the flat into his wife's (Gabi) name.

Overnight, Eren's crypto-trading booms and he makes a lot of profit. He invites the other couple to a nightclub to celebrate. After much drinking both couples get into arguments with their respective partners and decide that they have had enough of their partners and want to leave them for good.

Following this, Eren leaves Gabi and Sandra tells Armin she is leaving him and moving away.

Both Sandra and Gabi want to know about their share in their respective homes. Sandra is concerned that she was never put on the legal title. Eren is insisting that he gets the flat back and Gabi receive nothing, as she has not contributed a penny towards the flat.

Advise Sandra and Eren using relevant case law.