don't be so damn hard on yourself. Decluttering isn't the be-all, end-all in this life - I know that sounds like a cliche, but it bears repeating. To me, it sounds like you're not yet ready to give up these tokens, and you know what? that's COMPLETELY fine. When (note: when, not 'if') you meet someone new and begin to feel hopeful about things again, these objects won't have quite the same emotional weight, and you will be much better able to judge whether or not you need them anymore. But for now, when I read that last sentence, I see someone who is nowhere near happy with her current situation or ready to accept it (which is understandable) and who I think will gain no psychological benefits from eliminating these items.
The whole thing about keeping items that only bring you joy to look at or however else it is put is all very well, but as a tool to judge whether or not any specific items should be kept, it definitely has its limitations; most of all, because not ALL items we need to keep are about bringing us joy (and I'm not just talking about stuff like banks statements or a hoover that you keep for practical reasons). A lot of the time, what we keep is a result of more complex concerns about where we are in life and where we are going, and how far along the way we are.
One more consideration: none of the items mentioned are run-of-the-mill trinkets whose value is ONLY about who gave them to you - not the books, especially as they were judiciously selected to reflect your interests, and certainly not the portrait, either. So it's not like you're holding on to random bits of clutter with no inherent value to you other than who gave them to you. Picture it this way: if these books were given to you by a friend, not a boyfriend, with whom you later simply drifted apart with no hard feelings either side, you wouldn't have much of a specific reason to get rid of them. So wait, and remember that while it IS possible to change your mind about decluttering something you've kept, the reverse is not true, especially with objects of sentimental value - for those, once it's gone, it's gone for good.
At the end of the day, if you're stressing out about these taking up space, try to declutter something else of similar volume. And if you're so far along your path to clutter free living that you CAN'T find something of comparable volume to declutter, then I reckon you just don't need to worry about it altogether :-)
