2 Ragdolls not getting along

I have an 11 month spayed female ragdoll and recently got a 3 month old ragdoll boy who is now nearly 5 months old.

Our resident ragdoll, Lola, does not seem to like her new brother. We followed the Jackson Galaxy method. We have feliway diffuser. They have completely separate spaces.

It’s been 6 weeks now and they cannot tolerate any longer than 45 minutes - 1 hour together. Jasper (the kitten) doesn’t read signals very well and when Lola gets overstimulated and has had enough play time, Jasper doesn’t get the hint. We’ve tried separating them before things escalate, we’ve also tried letting Lola tell him off a little bit but that also doesn’t work. We’ve been stuck in this stage for about 2 weeks now.

I’m out the house for about 4-6 hours per day, rarely longer than that and they are separated during this time.

Would fixing Jasper help? I don’t want to fix him too early and ideally want to wait a few more months but at the same time I desperately want for Lola to realise he isn’t a threat and to get along with him.

She hasn’t been her usual, cuddly self. We got Jasper as a friend for her (mainly, but we also did want another cat) and we thought she would love it as she is very sociable and playful. But since Jasper came along, she rarely cuddles and isn’t overly interested in playing.

I want to help them both settle in and at least tolerate each other. What’s my best options?