The trick to keeping bikes in the house is a " space audit".
Go round the house and assess the percentage space taken up with your stuff vs your partners.
Things to remember to include are....
1. Clothes, shoes and handbags. Normally a huge space hog. You can also legitimately claim back the space for 50% of your clothes, because, frankly, you never would have bought them.
2. All kitchen stuff. Think about it; if you lived on your own you would have a pint glass, a fork, plastic plate and a can opener. The rest is a legit claim.
3. Ornaments. Well nuff said really.
4. Any rooms occupied by children or their stuff. There's a high degree of probability that they and their space hogging is entirely the volition of the dorris.....q.e.d....
Once tabulated, present your findings (i personally go for a full over head projector pie / venn diagrams and handouts) this normally proves that the house you " share" is frankly being hogged by your partner and there's at least enough m2 " owed" to you for several bikes.
Good luck, stay strong and if all else fails, withdraw sexual services till its fixed.