From The Collaborative International Dictionary of English v.0.48 :
Sentimentalist \Sen`ti*men"tal*ist\, n. [Cf. F.
sentimentaliste.]
One who has, or affects, sentiment or fine feeling.
[1913 Webster]
From WordNet (r) 3.0 (2006) :
sentimentalist
n 1: someone who indulges in excessive sentimentality [syn:
sentimentalist, romanticist]