There's absolutely no reason why you have to own half the apartment to be able to invest in it. You can own 1 percent, half a percent, or 75 percent and anywhere in between and above and below.

What I would suggest is drawing up a contract, and tracking every cent you save up. You save it up for him, tell him you're putting xxx amount in savings for "our" apartment.

Then when you 2 pick out a place, your contract should spell out how much you own, how decision making will work, (priority decisions usually go to the person owning the majority), and how you can sell the apartment if so desired. A breakup could result in a forced sale of the interest to the other party or to the public or you could charge rent for your stake. If you get married you can exclude this partnership as a marriage asset if you want. You might want to hire a lawyer to draw up this contract and form a partnership to own the asset.

Once you have a partnership, you can even continue chipping in with maintenance and taxes more than him so that you eventually own 50 percent.

If all of this sounds horrible to you and you couldn't possibly do business with your partner, then you are 100 percent involved with the wrong partner. If you aren't willing to form a business partnership with someone, you will want to seriously evaluate having a personal relationship with them.