Further to the Iberian question let's look at OTL in 1152.
Alfonso "the Emperor of All Spain" is widowed and looking for a wife from HRE as an alliance, his eldest son Sancho is recently married to Blanche daughter of his vassal King Garcia of Navarre, his second son Ferdinand is unmarried. He's trying to keep Portugal inside his kingdom of Leon, control Aragon while also expanding control to the Hispanic March / Catalan Counties, and keep pushing south.
How would Aquitaine fit into this?
Alfonso is King of Galicia, Leon, Castile, and Toledo. His eldest is entitled to Castile by Castilian tradition, and Spanish tradition entitled all his sons to a piece of the realm.
So his options are:
1) same as OTL
2) marry Eleanor himself and marry Ferdinand to a HRE lass
3) marry Ferdinand to Eleanor
The second best suits Eleanor but gives no benefit to Alfonso as may cause Garcia to rebel.
The third suits Alfonso better but might not benefit Eleanor if Ferdinand is too busy with whatever crown he gets (at least Galicia).