I'm honestly curious about this wanting to be a love interest's one and only true love. Is this just part of some sort of fantasy game fulfillment, or are people that way in real life, too? Maybe it's an age and perception thing?
I personally like the idea of characters (love interest or otherwise) having had lives outside of whatever you are currently doing to save the world. Especially when they are older characters, expecting them to never have loved and lost, or loved, kept, and procreated is strange. It may be beyond the scope of a video game or its audience's interest to get into, but casual reference to the wife/husband at home or how they hope to see their kids again sometime soon is not something I would hate to see. Kind of like Bailey in ME talking about his ex wife and children.
Coffee should kick in soon, honest...
Have to say, I sort of share this feeling. Nothing wrong with having one or two inexperienced companions, when it comes to relationships/love/romance. But most having a "fuller" background, especially if they have a few years under their belt, is more appealing to me. Cullen, by nature of the two games we have seen him in, still is most likely fairly "inexperienced". Even Cassandra may have a bit of that, based on how I imagine (and I admit, this just
my perception of her character) she prioritizes her life. I guess my main point is, I hope there is a nice broad spectrum. Some with little to no experience with romance, others with some understanding of longer termed romances (possibly even still in one), and those that have a lion's share of experience. lol!
As for Solas, even though he appears to be painted as a loner (at least that is a theory), it may not have always been that way for him. I personally like the idea of him having had some normalcy in his youth. As to what placed him in the (potential) position of being a hermit of sorts, the sky is the limit on the possibilities.

It could make for a very interesting story.
Oh, and as for the dead spouse/lover, would prefer a twist similar to Oghren's instead (the likes of Branka leaving him, or him leaving Felsi). Mostly because, it too can have an interesting outcome.
Just my .02 while finishing my coffee. Now I need a refill.