I took a break from typing lists and 'hard facts' into my Sunshine Islands Guides in order to record the Proposal Event with Shea and subsequent Wedding a week later:
Once again, Freya reloaded afterwards and remained single. I have recorded Denny's Events as well now.
Later: For all the players who have had trouble with Marriage in Sunshine Islands, there ARE requirements apart from the usual Harvest Moon general requirements in terms of Heart Level (deepest red), experiencing all Heart Events (the last of which is the 'date' in SI), having raised Mystic Islands, met the Harvest Goddess as well as Nathan and Alisa, buying the Spouse Bed and having a Blue Feather to make your Proposal.
In every case, you must have received ALL the Sun Stones that the individual has to offer. In other words, you must have obtained the Eligible Girl's/Bachelor's Personal Sun Stone and his/her Owner Sun Stone (if he/she IS head of household or owner of a home). In Shea's case, there is an added requirement in that you need to have obtained Wada's Sun Stone as well.
The reason for this is logical, actually. After marriage, your Spouse will live with YOU. This means that he/she no longer will live at the old address and you therefore cannot hope to trigger the Event that yields the owner Sun Stone any longer. In Lily's case, although she simply has a guest room at the Inn, she does have her own 'Owner' Sun Stone as well as her Personal Sun Stone. Will has one for his Ship... individuals who do not possess them include Natalie and Elliot as it is Taro who holds the Head of Household Sun Stone in THAT family.
Incidentally, if you are using cheats to obtain your Sun Stones, God help you, because I certainly can't. I strongly advise against the use of Cheats in any Harvest Moon or Rune Factory game. These games have too many variables to allow for cheats to be effective. Inevitably, something will not work... and it could be your chance to marry!