Are there any synonyms for the noun 'crush'?

I must clarify, when I say 'crush', I mean the subject of an unrealistic, one-sided infatuation. For example, it can be used in this sentence: 'My celebrity crush is David Beckham.'

Could that word be interchanged for another? Preferably, can it be a word which is not necessarily too formal/complex? I've searched online for a while but can't find any synonyms for this form of 'crush.'

I want the word for a novel which is set in an old-ish fantasy period so I don't think 'crush' would feel in-place. The main character is a lower-class worker.

Try yearning It would fit in a fantasy story in a long-ago setting.

Gwyneth had a powerful yearning for Sir Mortimer, a yearning she knew she must keep to herself. (made up)

Yearning, from The Free Dictionary

A persistent, often melancholy desire; a longing

Example, from Henry David Thoreau.

I do not know of any poetry to quote which adequately expresses this yearning for the Wild

To substantiate that it is an old word with an old flavor, see Etomonline

yearning.yearning (n.) Old English gierning, verbal noun from yearn (v.).

yearn (v.) English giernan (West Saxon), geornan (Mercian), giorna (Northumbrian) "to strive, be eager, desire, seek for, beg, demand," from Proto-Germanic *gernjan (source also of Gothic gairnjan "to desire," German begehren "to desire;" Old High German gern, Old Norse gjarn "desirous," Old English georn "eager, desirous," German gern "gladly, willingly"), from PIE root *gher- "to like, want"

While not a noun, you could use the verb moon

Act in a dreamily infatuated manner: Timothy’s mooning over her like a schoolboy

Oxford Dictionaries Online

It is often used as a phrasal verb with over and an object, although it can be used without, as in Stop mooning!

Besotted would fit the context

besotted

completely in love with someone and always thinking of them : He was so completely besotted with her that he couldn't see how badly she treated him

http://dictionary.cambridge.org/dictionary/english/besotted

Given the setting, the language and grammar are usually very differently formed from modern English, hence:

'I am truly besotted with Sir Beckham of Stow-on-the-Wold.'