Hi Nailler
There are quite a few creative options open to you. None might work, but you should investigate them all if you like the house and want to keep it.
1) Buy your partner's share of the house. The cost to you will be €250k. His mortgage is €175k, so you will have to keep his share of the mortgage and borrow a further €75k. Correction: There is no stamp duty on your purchase of the balance of the house as you were a first time buyer when you bought your first interest in it.
You should keep your permanent job for the moment if possible as it will make the bank more comfortable in dealing with you.
You should speak to your current lender who would be the most likely to grant you such an increase.
2) If you are getting on well with your ex-partner, and if he is not buying a house immediately, he may be happy to retain his interest until he is ready to buy a house. That way he retains a foothold in the property market.
When he is ready to buy a house, the sums may have changed. The house may have fallen in value, in which case you won't have to borrow so much. You may have got a salary increase which might help you stretch to the mortgage.
3) If he insists on selling now, can you find someone else to buy his half of the house? You will be in the same position as before, except that you will now be sharing with a co-owner rather than with a partner.
3a) Can you find somone who is looking for a property investment to buy out your partner? You would have to pay them some form of rent for their half of the house but you could get this by renting a room.
Brendan