Spousal Maintenance and the future

It's not quite one rule for you and another for your ex as your ex isn't actually asking that you support him financially at any point.
I do however understand your concerns with a young child, and how it might affect future relationships. Although LMM made a point about 6 month relationships being short, that's not the point here. I am sure that most of us on here wouldn't rush into any new relationship after our experiences and would spend a good amount of time getting to know future partners before moving them in. It's only after 6 months of living together that SM would cease, not 6 months of having a relationship.
Difficult as it is, try and see the other side of this argument. Whilst it might seem unfair to you that your ex is benefiting from 2 incomes, how would you feel if you met a man and his ex-wife expected you to cover any shortfall in his income. It's also not fair to expect your ex to be on standby with his money for an unlimited period of time.
I would try and leave the ex's partner out of this as much as it possible. A court would only look at cohabiting in terms of savings made on rent and bills by it being shared rather than taken on solely. Her finances are really nothing to do with you.

Happy days

The story is a bit more involved. He is currently claiming he cannot afford spousal maintainance as he has just brought himself a £760K property to house himself and his new partner. He is also saying he cannot pay CSA backpayments due, he is supporting another woman above his children, how can that be regarded as fair or morally right.

Its disgusting. My ex moved in with his girlfriend the day after he met her and then stopped payinng SM(long story but basically because I wouldn't take him back. I eventually had to take him to court but in the meantime I had to borrow money.

My ex also used to pay £10 each per month mobile phone for our 3 children. He stopped that as well.

Some exes I think feel when they have started a new relationship they shouldn't have to have anything to do with the old one.

My ex works and his girlfriend does and they live inn a house mortgage free. Saw photos recently where he was "father of the bride" to his girlfriends daughter. Im sure some of "his" money went into that! However, I hope he made the most of it because due to the way he has/is behaving our girls certainly (at the moment at least) don't want him to give them away at their weddings.

I am unemployed and on the breadline.

Some exes have the morals of an alleycat unfortunately!

Dont forget if your still married you own his 'new' property too and if he is over housed I am sure the judge will see what he is trying and compensate you accordingly.