Maturity has nothing to do with "letting go". It's all fine and good to say how we'd just get over it and move on with life, but the fact remains that the majority of people will go a bit insane over a lover at least once (if not more) and have difficulty letting go. It's not uncommon and shouldn't be seen as abnormal.
( for what it's worth, had I been "mature" and "let go", my hubs and I wouldn't be together now )
Casting more than one spell isn't going to make it work any faster, so I would suggest leaving it at 1 spell.
I think it's important for people to keep in mind that love spells do not create love. They create the situation for love to grow and be shown (love is not an emotion, it's a verb). At the end of the day, if two people are not a good match, they will separate again and again.