Spoiler
She actually was married to him in her first life and lived happily together
And the reason for her unfortunate marriages in her 2nd and 3rd life was because ,they were simply not her fate
So she'll be happy in this life (4th)since carcel is her FATE
So why did she regress the first time if she already had a happy life with him?
Major spoiler for their 1st life ~
Well I wouldn’t say it was a "happy life" since it wasn’t but she was happy nonetheless even though they went through so much (a lot actually)
Carcel died in battle and Ines died from her weak body. They both died at the same time. Carcel felt guilty he couldn't be with Ines when she died. (Ines had prayed so much to let her die if Carcel dies and he died in war so she died too. Either way she was going to die since she was very sick.) He was upset he left his wife waiting for him until the end. After their death, in the state of purgatory
the apostle Anastasio granted them each a prayer(he felt sorry for them)
Carcel originally wished to marry her again but Anastasio told him that his wife had already made the wish for him to be with someone else so he prayed to let Ines be happy, let her have a healthier body so she can enjoy herself. He was (somewhat) willing to let her marry someone else if she can be happy, but if the other man can't make her happy, he wants her to give him another chance to be with her again. He also prayed he won't fall in love with anyone else if it's not Ines, or marry anyone else if it's not her. Ines prayed that Carcel can find a woman he can love again and have kids he had never had before, and lived with them for a long time.
In the end, both their prayers got fulfilled through time and now they live happily together
I see, thanks for the explanation. They do deserve to be happy
getting carcel only at the 3rd time i hope our pretty inez will always be protected and surrounded by love from her equally pretty husband and future kids