So the site with the half built house has a potential buyer and i asked him what he would do with the funds if it went through and he said Id either bank it or invest in another property??
I am not sure I understand this comment. Are you saying that he should be instead putting the money towards your house, even though you said you don't want him too?
Is the 'another property' he talks of the one that he wants to buy together with you?
If he has property bought before he met you, isn't he equally entitled to retain the money he makes on selling it rather than sharing it with you, just like you want to retain ownership of your house and not give part of it away to him. It seems like you are saying that you want to keep your property for yourself, but expect him to use his funds from his property to contribute rent. Rent which you said you did not want. Surely if he pays you regular rent then it could be argued that he has contributed to the household expenses and could make a partial claim on your home anyway?
If he sold his property, would it raise enough for him to use as a deposit on a home for himself? In which case then paying rent to you instead of a mortgage means he is losing the opportunity to own his own property, and he would presumably build up equity on this property in the next few years, again if he were not living with you.
I thiink that there are some issues that you need to discuss, but I think you need to look at it from his POV as well. You could end the relationship tomorrow and chuck him out, he has no security in that respact.
An appointment with a solicitor to discuss the legalities of it, then a long chat with him, are in order.
Personally, as posters upthread have mentioned, I do not get any sense that you actually are in love with this man. Maybe that is really the issue here!