May a couple get engaged and have a L’Chaim during the 9 Days?
Engagement – Yes.
L’Chaim – only if it is small with a bit of refreshments. A normal style L’Chaim may not be made. Other restrictions (such as dancing, listening to music, eating meat and drinking wine) still apply even at a L’Chaim during this period.
שו״ע או״ח תקנא, ב. משנ״ב טז.